# class Module

A `Module` is a collection of methods and constants. The methods in a module may be instance methods or module methods. Instance methods appear as methods in a class when the module is included, module methods do not. Conversely, module methods may be called without creating an encapsulating object, while instance methods may not. (See `Module#module_function`.)

In the descriptions that follow, the parameter sym refers to a symbol, which is either a quoted string or a `Symbol` (such as `:name`).

    module Mod
      include Math
      CONST = 1
      def meth
        #  ...
      end
    end
    Mod.class              #=> Module
    Mod.constants          #=> [:CONST, :PI, :E]
    Mod.instance_methods   #=> [:meth]

### Public Class Methods

constants → array click to toggle source
constants(inherited) → array

In the first form, returns an array of the names of all constants accessible from the point of call. This list includes the names of all modules and classes defined in the global scope.

    Module.constants.first(4)
       # => [:ARGF, :ARGV, :ArgumentError, :Array]

    Module.constants.include?(:SEEK_SET)   # => false

    class IO
      Module.constants.include?(:SEEK_SET) # => true
    end

The second form calls the instance method `constants`.

    static VALUE
    rb_mod_s_constants(int argc, VALUE *argv, VALUE mod)
    {
        const rb_cref_t *cref = rb_vm_cref();
        VALUE klass;
        VALUE cbase = 0;
        void *data = 0;

        if (argc > 0 || mod != rb_cModule) {
            return rb_mod_constants(argc, argv, mod);
        }

        while (cref) {
            klass = CREF_CLASS(cref);
            if (!CREF_PUSHED_BY_EVAL(cref) &&
                !NIL_P(klass)) {
                data = rb_mod_const_at(CREF_CLASS(cref), data);
                if (!cbase) {
                    cbase = klass;
                }
            }
            cref = CREF_NEXT(cref);
        }

        if (cbase) {
            data = rb_mod_const_of(cbase, data);
        }
        return rb_const_list(data);
    }

nesting → array click to toggle source

Returns the list of `Modules` nested at the point of call.

    module M1
      module M2
        $a = Module.nesting
      end
    end
    $a           #=> [M1::M2, M1]
    $a[0].name   #=> "M1::M2"

    static VALUE
    rb_mod_nesting(void)
    {
        VALUE ary = rb_ary_new();
        const rb_cref_t *cref = rb_vm_cref();

        while (cref && CREF_NEXT(cref)) {
            VALUE klass = CREF_CLASS(cref);
            if (!CREF_PUSHED_BY_EVAL(cref) &&
                !NIL_P(klass)) {
                rb_ary_push(ary, klass);
            }
            cref = CREF_NEXT(cref);
        }
        return ary;
    }

new → mod click to toggle source
new {|mod| block } → mod

Creates a new anonymous module. If a block is given, it is passed the module object, and the block is evaluated in the context of this module like `module_eval`.

    fred = Module.new do
      def meth1
        "hello"
      end
      def meth2
        "bye"
      end
    end
    a = "my string"
    a.extend(fred)   #=> "my string"
    a.meth1          #=> "hello"
    a.meth2          #=> "bye"

Assign the module to a constant (name starting uppercase) if you want to treat it like a regular module.

    static VALUE
    rb_mod_initialize(VALUE module)
    {
        if (rb_block_given_p()) {
            rb_mod_module_exec(1, &module, module);
        }
        return Qnil;
    }

used_modules → array click to toggle source

Returns an array of all modules used in the current scope. The ordering of modules in the resulting array is not defined.

    module A
      refine Object do
      end
    end

    module B
      refine Object do
      end
    end

    using A
    using B
    p Module.used_modules

produces:

    [B, A]

    static VALUE
    rb_mod_s_used_modules(void)
    {
        const rb_cref_t *cref = rb_vm_cref();
        VALUE ary = rb_ary_new();

        while(cref) {
            if(!NIL_P(CREF_REFINEMENTS(cref))) {
                rb_hash_foreach(CREF_REFINEMENTS(cref), used_modules_i, ary);
            }
            cref = CREF_NEXT(cref);
        }

        return rb_funcall(ary, rb_intern("uniq"), 0);
    }

### Public Instance Methods

mod < other → true, false, or nil click to toggle source

Returns true if mod is a subclass of other. Returns `nil` if there's no relationship between the two. (Think of the relationship in terms of the class definition: “class A < B” implies “A < B”.)

    static VALUE
    rb_mod_lt(VALUE mod, VALUE arg)
    {
        if (mod == arg) return Qfalse;
        return rb_class_inherited_p(mod, arg);
    }

mod <= other → true, false, or nil click to toggle source

Returns true if mod is a subclass of other or is the same as other. Returns `nil` if there's no relationship between the two. (Think of the relationship in terms of the class definition: “class A < B” implies “A < B”.)

    VALUE
    rb_class_inherited_p(VALUE mod, VALUE arg)
    {
        if (mod == arg) return Qtrue;
        if (!CLASS_OR_MODULE_P(arg) && !RB_TYPE_P(arg, T_ICLASS)) {
            rb_raise(rb_eTypeError, "compared with non class/module");
        }
        if (class_search_ancestor(mod, RCLASS_ORIGIN(arg))) {
            return Qtrue;
        }
        /* not mod < arg; check if mod > arg */
        if (class_search_ancestor(arg, mod)) {
            return Qfalse;
        }
        return Qnil;
    }

module <=> other_module → -1, 0, +1, or nil click to toggle source

Comparison—Returns -1, 0, +1 or nil depending on whether `module` includes `other_module`, they are the same, or if `module` is included by `other_module`.

Returns `nil` if `module` has no relationship with `other_module`, if `other_module` is not a module, or if the two values are incomparable.

    static VALUE
    rb_mod_cmp(VALUE mod, VALUE arg)
    {
        VALUE cmp;

        if (mod == arg) return INT2FIX(0);
        if (!CLASS_OR_MODULE_P(arg)) {
            return Qnil;
        }

        cmp = rb_class_inherited_p(mod, arg);
        if (NIL_P(cmp)) return Qnil;
        if (cmp) {
            return INT2FIX(-1);
        }
        return INT2FIX(1);
    }

obj == other → true or false click to toggle source
equal?(other) → true or false
eql?(other) → true or false

Equality — At the `Object` level, `==` returns `true` only if `obj` and `other` are the same object. Typically, this method is overridden in descendant classes to provide class-specific meaning.

Unlike `==`, the `equal?` method should never be overridden by subclasses as it is used to determine object identity (that is, `a.equal?(b)` if and only if `a` is the same object as `b`):

    obj = "a"
    other = obj.dup

    obj == other      #=> true
    obj.equal? other  #=> false
    obj.equal? obj    #=> true

The `eql?` method returns `true` if `obj` and `other` refer to the same hash key. This is used by Hash to test members for equality. For objects of class `Object`, `eql?` is synonymous with `==`. Subclasses normally continue this tradition by aliasing `eql?` to their overridden `==` method, but there are exceptions. `Numeric` types, for example, perform type conversion across `==`, but not across `eql?`, so:

    1 == 1.0     #=> true
    1.eql? 1.0   #=> false

    VALUE
    rb_obj_equal(VALUE obj1, VALUE obj2)
    {
        if (obj1 == obj2) return Qtrue;
        return Qfalse;
    }

mod === obj → true or false click to toggle source

Case Equality—Returns `true` if obj is an instance of mod or an instance of one of mod's descendants. Of limited use for modules, but can be used in `case` statements to classify objects by class.

    static VALUE
    rb_mod_eqq(VALUE mod, VALUE arg)
    {
        return rb_obj_is_kind_of(arg, mod);
    }

mod > other → true, false, or nil click to toggle source

Returns true if mod is an ancestor of other. Returns `nil` if there's no relationship between the two. (Think of the relationship in terms of the class definition: “class A < B” implies “B > A”.)

    static VALUE
    rb_mod_gt(VALUE mod, VALUE arg)
    {
        if (mod == arg) return Qfalse;
        return rb_mod_ge(mod, arg);
    }

mod >= other → true, false, or nil click to toggle source

Returns true if mod is an ancestor of other, or the two modules are the same. Returns `nil` if there's no relationship between the two. (Think of the relationship in terms of the class definition: “class A < B” implies “B > A”.)

    static VALUE
    rb_mod_ge(VALUE mod, VALUE arg)
    {
        if (!CLASS_OR_MODULE_P(arg)) {
            rb_raise(rb_eTypeError, "compared with non class/module");
        }

        return rb_class_inherited_p(arg, mod);
    }

alias_method(new_name, old_name) → self click to toggle source

Makes new_name a new copy of the method old_name. This can be used to retain access to methods that are overridden.

    module Mod
      alias_method :orig_exit, :exit
      def exit(code=0)
        puts "Exiting with code #{code}"
        orig_exit(code)
      end
    end
    include Mod
    exit(99)

produces:

    Exiting with code 99

    static VALUE
    rb_mod_alias_method(VALUE mod, VALUE newname, VALUE oldname)
    {
        ID oldid = rb_check_id(&oldname);
        if (!oldid) {
            rb_print_undef_str(mod, oldname);
        }
        rb_alias(mod, rb_to_id(newname), oldid);
        return mod;
    }

ancestors → array click to toggle source

Returns a list of modules included/prepended in mod (including mod itself).

    module Mod
      include Math
      include Comparable
      prepend Enumerable
    end

    Mod.ancestors        #=> [Enumerable, Mod, Comparable, Math]
    Math.ancestors       #=> [Math]
    Enumerable.ancestors #=> [Enumerable]

    VALUE
    rb_mod_ancestors(VALUE mod)
    {
        VALUE p, ary = rb_ary_new();

        for (p = mod; p; p = RCLASS_SUPER(p)) {
    	if (BUILTIN_TYPE(p) == T_ICLASS) {
    	    rb_ary_push(ary, RBASIC(p)->klass);
    	}
    	else if (p == RCLASS_ORIGIN(p)) {
    	    rb_ary_push(ary, p);
    	}
        }
        return ary;
    }

attr(name, ...) → nil click to toggle source
attr(name, true) → nil
attr(name, false) → nil

The first form is equivalent to `attr_reader`. The second form is equivalent to `attr_accessor(name)` but deprecated. The last form is equivalent to `attr_reader(name)` but deprecated.

    VALUE
    rb_mod_attr(int argc, VALUE *argv, VALUE klass)
    {
        if (argc == 2 && (argv[1] == Qtrue || argv[1] == Qfalse)) {
            rb_warning("optional boolean argument is obsoleted");
            rb_attr(klass, id_for_attr(klass, argv[0]), 1, RTEST(argv[1]), TRUE);
            return Qnil;
        }
        return rb_mod_attr_reader(argc, argv, klass);
    }

attr_accessor(symbol, ...) → nil click to toggle source
attr_accessor(string, ...) → nil

Defines a named attribute for this module, where the name is symbol.`id2name`, creating an instance variable (`@name`) and a corresponding access method to read it. Also creates a method called `name=` to set the attribute. String arguments are converted to symbols.

    module Mod
      attr_accessor(:one, :two)
    end
    Mod.instance_methods.sort   #=> [:one, :one=, :two, :two=]

    static VALUE
    rb_mod_attr_accessor(int argc, VALUE *argv, VALUE klass)
    {
        int i;

        for (i=0; i<argc; i++) {
            rb_attr(klass, id_for_attr(klass, argv[i]), TRUE, TRUE, TRUE);
        }
        return Qnil;
    }

attr_reader(symbol, ...) → nil click to toggle source
attr(symbol, ...) → nil
attr_reader(string, ...) → nil
attr(string, ...) → nil

Creates instance variables and corresponding methods that return the value of each instance variable. Equivalent to calling “`attr`:name'' on each name in turn. String arguments are converted to symbols.

    static VALUE
    rb_mod_attr_reader(int argc, VALUE *argv, VALUE klass)
    {
        int i;

        for (i=0; i<argc; i++) {
            rb_attr(klass, id_for_attr(klass, argv[i]), TRUE, FALSE, TRUE);
        }
        return Qnil;
    }

attr_writer(symbol, ...) → nil click to toggle source
attr_writer(string, ...) → nil

Creates an accessor method to allow assignment to the attribute symbol`.id2name`. String arguments are converted to symbols.

    static VALUE
    rb_mod_attr_writer(int argc, VALUE *argv, VALUE klass)
    {
        int i;

        for (i=0; i<argc; i++) {
            rb_attr(klass, id_for_attr(klass, argv[i]), FALSE, TRUE, TRUE);
        }
        return Qnil;
    }

autoload(module, filename) → nil click to toggle source

Registers filename to be loaded (using `Kernel::require`) the first time that module (which may be a `String` or a symbol) is accessed in the namespace of mod.

    module A
    end
    A.autoload(:B, "b")
    A::B.doit            # autoloads "b"

    static VALUE
    rb_mod_autoload(VALUE mod, VALUE sym, VALUE file)
    {
        ID id = rb_to_id(sym);

        FilePathValue(file);
        rb_autoload_str(mod, id, file);
        return Qnil;
    }

autoload?(name) → String or nil click to toggle source

Returns filename to be loaded if name is registered as `autoload` in the namespace of mod.

    module A
    end
    A.autoload(:B, "b")
    A.autoload?(:B)            #=> "b"

    static VALUE
    rb_mod_autoload_p(VALUE mod, VALUE sym)
    {
        ID id = rb_check_id(&sym);
        if (!id) {
            return Qnil;
        }
        return rb_autoload_p(mod, id);
    }

class_eval(string [, filename [, lineno]]) → obj click to toggle source
class_eval {|mod| block } → obj

Evaluates the string or block in the context of mod, except that when a block is given, constant/class variable lookup is not affected. This can be used to add methods to a class. `module_eval` returns the result of evaluating its argument. The optional filename and lineno parameters set the text for error messages.

    class Thing
    end
    a = %q{def hello() "Hello there!" end}
    Thing.module_eval(a)
    puts Thing.new.hello()
    Thing.module_eval("invalid code", "dummy", 123)

produces:

    Hello there!
    dummy:123:in `module_eval': undefined local variable
        or method `code' for Thing:Class

    VALUE
    rb_mod_module_eval(int argc, const VALUE *argv, VALUE mod)
    {
        return specific_eval(argc, argv, mod, mod);
    }

class_exec(arg...) {|var...| block } → obj click to toggle source

Evaluates the given block in the context of the class/module. The method defined in the block will belong to the receiver. Any arguments passed to the method will be passed to the block. This can be used if the block needs to access instance variables.

    class Thing
    end
    Thing.class_exec{
      def hello() "Hello there!" end
    }
    puts Thing.new.hello()

produces:

    Hello there!

    VALUE
    rb_mod_module_exec(int argc, const VALUE *argv, VALUE mod)
    {
        return yield_under(mod, mod, argc, argv);
    }

class_variable_defined?(symbol) → true or false click to toggle source
class_variable_defined?(string) → true or false

Returns `true` if the given class variable is defined in obj. String arguments are converted to symbols.

    class Fred
      @@foo = 99
    end
    Fred.class_variable_defined?(:@@foo)    #=> true
    Fred.class_variable_defined?(:@@bar)    #=> false

    static VALUE
    rb_mod_cvar_defined(VALUE obj, VALUE iv)
    {
        ID id = id_for_var(obj, iv, a, class);

        if (!id) {
            return Qfalse;
        }
        return rb_cvar_defined(obj, id);
    }

class_variable_get(symbol) → obj click to toggle source
class_variable_get(string) → obj

Returns the value of the given class variable (or throws a `NameError` exception). The `@@` part of the variable name should be included for regular class variables. String arguments are converted to symbols.

    class Fred
      @@foo = 99
    end
    Fred.class_variable_get(:@@foo)     #=> 99

    static VALUE
    rb_mod_cvar_get(VALUE obj, VALUE iv)
    {
        ID id = id_for_var(obj, iv, a, class);

        if (!id) {
            rb_name_err_raise("uninitialized class variable %1$s in %2$s",
                              obj, iv);
        }
        return rb_cvar_get(obj, id);
    }

class_variable_set(symbol, obj) → obj click to toggle source
class_variable_set(string, obj) → obj

Sets the class variable named by symbol to the given object. If the class variable name is passed as a string, that string is converted to a symbol.

    class Fred
      @@foo = 99
      def foo
        @@foo
      end
    end
    Fred.class_variable_set(:@@foo, 101)     #=> 101
    Fred.new.foo                             #=> 101

    static VALUE
    rb_mod_cvar_set(VALUE obj, VALUE iv, VALUE val)
    {
        ID id = id_for_var(obj, iv, a, class);
        if (!id) id = rb_intern_str(iv);
        rb_cvar_set(obj, id, val);
        return val;
    }

class_variables(inherit=true) → array click to toggle source

Returns an array of the names of class variables in mod. This includes the names of class variables in any included modules, unless the inherit parameter is set to `false`.

    class One
      @@var1 = 1
    end
    class Two < One
      @@var2 = 2
    end
    One.class_variables          #=> [:@@var1]
    Two.class_variables          #=> [:@@var2, :@@var1]
    Two.class_variables(false)   #=> [:@@var2]

    VALUE
    rb_mod_class_variables(int argc, const VALUE *argv, VALUE mod)
    {
        VALUE inherit;
        st_table *tbl;

        if (argc == 0) {
    	inherit = Qtrue;
        }
        else {
    	rb_scan_args(argc, argv, "01", &inherit);
        }
        if (RTEST(inherit)) {
    	tbl = mod_cvar_of(mod, 0);
        }
        else {
    	tbl = mod_cvar_at(mod, 0);
        }
        return cvar_list(tbl);
    }

const_defined?(sym, inherit=true) → true or false click to toggle source
const_defined?(str, inherit=true) → true or false

Says whether mod or its ancestors have a constant with the given name:

    Float.const_defined?(:EPSILON)      #=> true, found in Float itself
    Float.const_defined?("String")      #=> true, found in Object (ancestor)
    BasicObject.const_defined?(:Hash)   #=> false

If mod is a `Module`, additionally `Object` and its ancestors are checked:

    Math.const_defined?(:String)   #=> true, found in Object

In each of the checked classes or modules, if the constant is not present but there is an autoload for it, `true` is returned directly without autoloading:

    module Admin
      autoload :User, 'admin/user'
    end
    Admin.const_defined?(:User)   #=> true

If the constant is not found the callback `const_missing` is not called and the method returns `false`.

If `inherit` is false, the lookup only checks the constants in the receiver:

    IO.const_defined?(:SYNC)          #=> true, found in File::Constants (ancestor)
    IO.const_defined?(:SYNC, false)   #=> false, not found in IO itself

In this case, the same logic for autoloading applies.

If the argument is not a valid constant name a `NameError` is raised with the message “wrong constant name name”:

    Hash.const_defined? 'foobar'   #=> NameError: wrong constant name foobar

    static VALUE
    rb_mod_const_defined(int argc, VALUE *argv, VALUE mod)
    {
        VALUE name, recur;
        rb_encoding *enc;
        const char *pbeg, *p, *path, *pend;
        ID id;

        rb_check_arity(argc, 1, 2);
        name = argv[0];
        recur = (argc == 1) ? Qtrue : argv[1];

        if (SYMBOL_P(name)) {
            if (!rb_is_const_sym(name)) goto wrong_name;
            id = rb_check_id(&name);
            if (!id) return Qfalse;
            return RTEST(recur) ? rb_const_defined(mod, id) : rb_const_defined_at(mod, id);
        }

        path = StringValuePtr(name);
        enc = rb_enc_get(name);

        if (!rb_enc_asciicompat(enc)) {
            rb_raise(rb_eArgError, "invalid class path encoding (non ASCII)");
        }

        pbeg = p = path;
        pend = path + RSTRING_LEN(name);

        if (p >= pend || !*p) {
          wrong_name:
            rb_name_err_raise(wrong_constant_name, mod, name);
        }

        if (p + 2 < pend && p[0] == ':' && p[1] == ':') {
            mod = rb_cObject;
            p += 2;
            pbeg = p;
        }

        while (p < pend) {
            VALUE part;
            long len, beglen;

            while (p < pend && *p != ':') p++;

            if (pbeg == p) goto wrong_name;

            id = rb_check_id_cstr(pbeg, len = p-pbeg, enc);
            beglen = pbeg-path;

            if (p < pend && p[0] == ':') {
                if (p + 2 >= pend || p[1] != ':') goto wrong_name;
                p += 2;
                pbeg = p;
            }

            if (!id) {
                part = rb_str_subseq(name, beglen, len);
                OBJ_FREEZE(part);
                if (!ISUPPER(*pbeg) || !rb_is_const_name(part)) {
                    name = part;
                    goto wrong_name;
                }
                else {
                    return Qfalse;
                }
            }
            if (!rb_is_const_id(id)) {
                name = ID2SYM(id);
                goto wrong_name;
            }
            if (RTEST(recur)) {
                if (!rb_const_defined(mod, id))
                    return Qfalse;
                mod = rb_const_get(mod, id);
            }
            else {
                if (!rb_const_defined_at(mod, id))
                    return Qfalse;
                mod = rb_const_get_at(mod, id);
            }
            recur = Qfalse;

            if (p < pend && !RB_TYPE_P(mod, T_MODULE) && !RB_TYPE_P(mod, T_CLASS)) {
                rb_raise(rb_eTypeError, "%"PRIsVALUE" does not refer to class/module",
                         QUOTE(name));
            }
        }

        return Qtrue;
    }

const_get(sym, inherit=true) → obj click to toggle source
const_get(str, inherit=true) → obj

Checks for a constant with the given name in mod. If `inherit` is set, the lookup will also search the ancestors (and `Object` if mod is a `Module`).

The value of the constant is returned if a definition is found, otherwise a `NameError` is raised.

    Math.const_get(:PI)   #=> 3.14159265358979

This method will recursively look up constant names if a namespaced class name is provided. For example:

    module Foo; class Bar; end end
    Object.const_get 'Foo::Bar'

The `inherit` flag is respected on each lookup. For example:

    module Foo
      class Bar
        VAL = 10
      end

      class Baz < Bar; end
    end

    Object.const_get 'Foo::Baz::VAL'         # => 10
    Object.const_get 'Foo::Baz::VAL', false  # => NameError

If the argument is not a valid constant name a `NameError` will be raised with a warning “wrong constant name”.

    Object.const_get 'foobar' #=> NameError: wrong constant name foobar

    static VALUE
    rb_mod_const_get(int argc, VALUE *argv, VALUE mod)
    {
        VALUE name, recur;
        rb_encoding *enc;
        const char *pbeg, *p, *path, *pend;
        ID id;

        rb_check_arity(argc, 1, 2);
        name = argv[0];
        recur = (argc == 1) ? Qtrue : argv[1];

        if (SYMBOL_P(name)) {
            if (!rb_is_const_sym(name)) goto wrong_name;
            id = rb_check_id(&name);
            if (!id) return rb_const_missing(mod, name);
            return RTEST(recur) ? rb_const_get(mod, id) : rb_const_get_at(mod, id);
        }

        path = StringValuePtr(name);
        enc = rb_enc_get(name);

        if (!rb_enc_asciicompat(enc)) {
            rb_raise(rb_eArgError, "invalid class path encoding (non ASCII)");
        }

        pbeg = p = path;
        pend = path + RSTRING_LEN(name);

        if (p >= pend || !*p) {
          wrong_name:
            rb_name_err_raise(wrong_constant_name, mod, name);
        }

        if (p + 2 < pend && p[0] == ':' && p[1] == ':') {
            mod = rb_cObject;
            p += 2;
            pbeg = p;
        }

        while (p < pend) {
            VALUE part;
            long len, beglen;

            while (p < pend && *p != ':') p++;

            if (pbeg == p) goto wrong_name;

            id = rb_check_id_cstr(pbeg, len = p-pbeg, enc);
            beglen = pbeg-path;

            if (p < pend && p[0] == ':') {
                if (p + 2 >= pend || p[1] != ':') goto wrong_name;
                p += 2;
                pbeg = p;
            }

            if (!RB_TYPE_P(mod, T_MODULE) && !RB_TYPE_P(mod, T_CLASS)) {
                rb_raise(rb_eTypeError, "%"PRIsVALUE" does not refer to class/module",
                         QUOTE(name));
            }

            if (!id) {
                part = rb_str_subseq(name, beglen, len);
                OBJ_FREEZE(part);
                if (!ISUPPER(*pbeg) || !rb_is_const_name(part)) {
                    name = part;
                    goto wrong_name;
                }
                else if (!rb_method_basic_definition_p(CLASS_OF(mod), id_const_missing)) {
                    part = rb_str_intern(part);
                    mod = rb_const_missing(mod, part);
                    continue;
                }
                else {
                    rb_mod_const_missing(mod, part);
                }
            }
            if (!rb_is_const_id(id)) {
                name = ID2SYM(id);
                goto wrong_name;
            }
            mod = RTEST(recur) ? rb_const_get(mod, id) : rb_const_get_at(mod, id);
        }

        return mod;
    }

const_missing(sym) → obj click to toggle source

Invoked when a reference is made to an undefined constant in mod. It is passed a symbol for the undefined constant, and returns a value to be used for that constant. The following code is an example of the same:

    def Foo.const_missing(name)
      name # return the constant name as Symbol
    end

    Foo::UNDEFINED_CONST    #=> :UNDEFINED_CONST: symbol returned

In the next example when a reference is made to an undefined constant, it attempts to load a file whose name is the lowercase version of the constant (thus class `Fred` is assumed to be in file `fred.rb`). If found, it returns the loaded class. It therefore implements an autoload feature similar to Kernel#autoload and #autoload.

    def Object.const_missing(name)
      @looked_for ||= {}
      str_name = name.to_s
      raise "Class not found: #{name}" if @looked_for[str_name]
      @looked_for[str_name] = 1
      file = str_name.downcase
      require file
      klass = const_get(name)
      return klass if klass
      raise "Class not found: #{name}"
    end

    VALUE
    rb_mod_const_missing(VALUE klass, VALUE name)
    {
        rb_vm_pop_cfunc_frame();
        uninitialized_constant(klass, name);

        UNREACHABLE;
    }

const_set(sym, obj) → obj click to toggle source
const_set(str, obj) → obj

Sets the named constant to the given object, returning that object. Creates a new constant if no constant with the given name previously existed.

    Math.const_set("HIGH_SCHOOL_PI", 22.0/7.0)   #=> 3.14285714285714
    Math::HIGH_SCHOOL_PI - Math::PI              #=> 0.00126448926734968

If `sym` or `str` is not a valid constant name a `NameError` will be raised with a warning “wrong constant name”.

    Object.const_set('foobar', 42) #=> NameError: wrong constant name foobar

    static VALUE
    rb_mod_const_set(VALUE mod, VALUE name, VALUE value)
    {
        ID id = id_for_setter(mod, name, const, wrong_constant_name);
        if (!id) id = rb_intern_str(name);
        rb_const_set(mod, id, value);

        return value;
    }

constants(inherit=true) → array click to toggle source

Returns an array of the names of the constants accessible in mod. This includes the names of constants in any included modules (example at start of section), unless the inherit parameter is set to `false`.

The implementation makes no guarantees about the order in which the constants are yielded.

    IO.constants.include?(:SYNC)        #=> true
    IO.constants(false).include?(:SYNC) #=> false

Also see `Module::const_defined?`.

    VALUE
    rb_mod_constants(int argc, const VALUE *argv, VALUE mod)
    {
        VALUE inherit;

        if (argc == 0) {
    	inherit = Qtrue;
        }
        else {
    	rb_scan_args(argc, argv, "01", &inherit);
        }

        if (RTEST(inherit)) {
    	return rb_const_list(rb_mod_const_of(mod, 0));
        }
        else {
    	return rb_local_constants(mod);
        }
    }

define_method(symbol, method) → symbol click to toggle source
define_method(symbol) { block } → symbol

Defines an instance method in the receiver. The method parameter can be a `Proc`, a `Method` or an `UnboundMethod` object. If a block is specified, it is used as the method body. This block is evaluated using `instance_eval`.

    class A
      def fred
        puts "In Fred"
      end
      def create_method(name, &block)
        self.class.define_method(name, &block)
      end
      define_method(:wilma) { puts "Charge it!" }
    end
    class B < A
      define_method(:barney, instance_method(:fred))
    end
    a = B.new
    a.barney
    a.wilma
    a.create_method(:betty) { p self }
    a.betty

produces:

    In Fred
    Charge it!
    #<B:0x401b39e8>

    static VALUE
    rb_mod_define_method(int argc, VALUE *argv, VALUE mod)
    {
        ID id;
        VALUE body;
        VALUE name;
        const rb_cref_t *cref = rb_vm_cref_in_context(mod, mod);
        const rb_scope_visibility_t default_scope_visi = {METHOD_VISI_PUBLIC, FALSE};
        const rb_scope_visibility_t *scope_visi = &default_scope_visi;
        int is_method = FALSE;

        if (cref) {
            scope_visi = CREF_SCOPE_VISI(cref);
        }

        rb_check_arity(argc, 1, 2);
        name = argv[0];
        id = rb_check_id(&name);
        if (argc == 1) {
    #if PROC_NEW_REQUIRES_BLOCK
            body = rb_block_lambda();
    #else
            const rb_execution_context_t *ec = GET_EC();
            VALUE block_handler = rb_vm_frame_block_handler(ec->cfp);
            if (block_handler == VM_BLOCK_HANDLER_NONE) rb_raise(rb_eArgError, proc_without_block);

            switch (vm_block_handler_type(block_handler)) {
              case block_handler_type_proc:
                body = VM_BH_TO_PROC(block_handler);
                break;
              case block_handler_type_symbol:
                body = rb_sym_to_proc(VM_BH_TO_SYMBOL(block_handler));
                break;
              case block_handler_type_iseq:
              case block_handler_type_ifunc:
                body = rb_vm_make_lambda(ec, VM_BH_TO_CAPT_BLOCK(block_handler), rb_cProc);
            }
    #endif
        }
        else {
            body = argv[1];

            if (rb_obj_is_method(body)) {
                is_method = TRUE;
            }
            else if (rb_obj_is_proc(body)) {
                is_method = FALSE;
            }
            else {
                rb_raise(rb_eTypeError,
                         "wrong argument type %s (expected Proc/Method)",
                         rb_obj_classname(body));
            }
        }
        if (!id) id = rb_to_id(name);

        if (is_method) {
            struct METHOD *method = (struct METHOD *)DATA_PTR(body);
            if (method->me->owner != mod && !RB_TYPE_P(method->me->owner, T_MODULE) &&
                !RTEST(rb_class_inherited_p(mod, method->me->owner))) {
                if (FL_TEST(method->me->owner, FL_SINGLETON)) {
                    rb_raise(rb_eTypeError,
                             "can't bind singleton method to a different class");
                }
                else {
                    rb_raise(rb_eTypeError,
                             "bind argument must be a subclass of % "PRIsVALUE,
                             method->me->owner);
                }
            }
            rb_method_entry_set(mod, id, method->me, scope_visi->method_visi);
            if (scope_visi->module_func) {
                rb_method_entry_set(rb_singleton_class(mod), id, method->me, METHOD_VISI_PUBLIC);
            }
            RB_GC_GUARD(body);
        }
        else {
            VALUE procval = proc_dup(body);
            if (vm_proc_iseq(procval) != NULL) {
                rb_proc_t *proc;
                GetProcPtr(procval, proc);
                proc->is_lambda = TRUE;
                proc->is_from_method = TRUE;
            }
            rb_add_method(mod, id, VM_METHOD_TYPE_BMETHOD, (void *)procval, scope_visi->method_visi);
            if (scope_visi->module_func) {
                rb_add_method(rb_singleton_class(mod), id, VM_METHOD_TYPE_BMETHOD, (void *)body, METHOD_VISI_PUBLIC);
            }
        }

        return ID2SYM(id);
    }

deprecate_constant(symbol, ...) → mod click to toggle source

Makes a list of existing constants deprecated.

    VALUE
    rb_mod_deprecate_constant(int argc, const VALUE *argv, VALUE obj)
    {
        set_const_visibility(obj, argc, argv, CONST_DEPRECATED, CONST_DEPRECATED);
        return obj;
    }

freeze → mod click to toggle source

Prevents further modifications to mod.

This method returns self.

    static VALUE
    rb_mod_freeze(VALUE mod)
    {
        rb_class_name(mod);
        return rb_obj_freeze(mod);
    }

include(module, ...) → self click to toggle source

Invokes `Module.append_features` on each parameter in reverse order.

    static VALUE
    rb_mod_include(int argc, VALUE *argv, VALUE module)
    {
        int i;
        ID id_append_features, id_included;

        CONST_ID(id_append_features, "append_features");
        CONST_ID(id_included, "included");

        rb_check_arity(argc, 1, UNLIMITED_ARGUMENTS);
        for (i = 0; i < argc; i++)
            Check_Type(argv[i], T_MODULE);
        while (argc--) {
            rb_funcall(argv[argc], id_append_features, 1, module);
            rb_funcall(argv[argc], id_included, 1, module);
        }
        return module;
    }

include?(module) → true or false click to toggle source

Returns `true` if module is included in mod or one of mod's ancestors.

    module A
    end
    class B
      include A
    end
    class C < B
    end
    B.include?(A)   #=> true
    C.include?(A)   #=> true
    A.include?(A)   #=> false

    VALUE
    rb_mod_include_p(VALUE mod, VALUE mod2)
    {
        VALUE p;

        Check_Type(mod2, T_MODULE);
        for (p = RCLASS_SUPER(mod); p; p = RCLASS_SUPER(p)) {
    	if (BUILTIN_TYPE(p) == T_ICLASS) {
    	    if (RBASIC(p)->klass == mod2) return Qtrue;
    	}
        }
        return Qfalse;
    }

included_modules → array click to toggle source

Returns the list of modules included in mod.

    module Mixin
    end

    module Outer
      include Mixin
    end

    Mixin.included_modules   #=> []
    Outer.included_modules   #=> [Mixin]

    VALUE
    rb_mod_included_modules(VALUE mod)
    {
        VALUE ary = rb_ary_new();
        VALUE p;
        VALUE origin = RCLASS_ORIGIN(mod);

        for (p = RCLASS_SUPER(mod); p; p = RCLASS_SUPER(p)) {
    	if (p != origin && BUILTIN_TYPE(p) == T_ICLASS) {
    	    VALUE m = RBASIC(p)->klass;
    	    if (RB_TYPE_P(m, T_MODULE))
    		rb_ary_push(ary, m);
    	}
        }
        return ary;
    }

inspect()
Alias for: to_s
instance_method(symbol) → unbound_method click to toggle source

Returns an `UnboundMethod` representing the given instance method in mod.

    class Interpreter
      def do_a() print "there, "; end
      def do_d() print "Hello ";  end
      def do_e() print "!\n";     end
      def do_v() print "Dave";    end
      Dispatcher = {
        "a" => instance_method(:do_a),
        "d" => instance_method(:do_d),
        "e" => instance_method(:do_e),
        "v" => instance_method(:do_v)
      }
      def interpret(string)
        string.each_char {|b| Dispatcher[b].bind(self).call }
      end
    end

    interpreter = Interpreter.new
    interpreter.interpret('dave')

produces:

    Hello there, Dave!

    static VALUE
    rb_mod_instance_method(VALUE mod, VALUE vid)
    {
        ID id = rb_check_id(&vid);
        if (!id) {
            rb_method_name_error(mod, vid);
        }
        return mnew(mod, Qundef, id, rb_cUnboundMethod, FALSE);
    }

instance_methods(include_super=true) → array click to toggle source

Returns an array containing the names of the public and protected instance methods in the receiver. For a module, these are the public and protected methods; for a class, they are the instance (not singleton) methods. If the optional parameter is `false`, the methods of any ancestors are not included.

    module A
      def method1()  end
    end
    class B
      include A
      def method2()  end
    end
    class C < B
      def method3()  end
    end

    A.instance_methods(false)                   #=> [:method1]
    B.instance_methods(false)                   #=> [:method2]
    B.instance_methods(true).include?(:method1) #=> true
    C.instance_methods(false)                   #=> [:method3]
    C.instance_methods.include?(:method2)       #=> true

    VALUE
    rb_class_instance_methods(int argc, const VALUE *argv, VALUE mod)
    {
        return class_instance_method_list(argc, argv, mod, 0, ins_methods_i);
    }

method_defined?(symbol) → true or false click to toggle source
method_defined?(string) → true or false

Returns `true` if the named method is defined by mod (or its included modules and, if mod is a class, its ancestors). Public and protected methods are matched. String arguments are converted to symbols.

    module A
      def method1()  end
      def protected_method1()  end
      protected :protected_method1
    end
    class B
      def method2()  end
      def private_method2()  end
      private :private_method2
    end
    class C < B
      include A
      def method3()  end
    end

    A.method_defined? :method1              #=> true
    C.method_defined? "method1"             #=> true
    C.method_defined? "method2"             #=> true
    C.method_defined? "method3"             #=> true
    C.method_defined? "protected_method1"   #=> true
    C.method_defined? "method4"             #=> false
    C.method_defined? "private_method2"     #=> false

    static VALUE
    rb_mod_method_defined(VALUE mod, VALUE mid)
    {
        ID id = rb_check_id(&mid);
        if (!id || !rb_method_boundp(mod, id, 1)) {
            return Qfalse;
        }
        return Qtrue;

    }

module_eval(string [, filename [, lineno]]) → obj click to toggle source
module_eval {|mod| block } → obj

Evaluates the string or block in the context of mod, except that when a block is given, constant/class variable lookup is not affected. This can be used to add methods to a class. `module_eval` returns the result of evaluating its argument. The optional filename and lineno parameters set the text for error messages.

    class Thing
    end
    a = %q{def hello() "Hello there!" end}
    Thing.module_eval(a)
    puts Thing.new.hello()
    Thing.module_eval("invalid code", "dummy", 123)

produces:

    Hello there!
    dummy:123:in `module_eval': undefined local variable
        or method `code' for Thing:Class

    VALUE
    rb_mod_module_eval(int argc, const VALUE *argv, VALUE mod)
    {
        return specific_eval(argc, argv, mod, mod);
    }

module_exec(arg...) {|var...| block } → obj click to toggle source

Evaluates the given block in the context of the class/module. The method defined in the block will belong to the receiver. Any arguments passed to the method will be passed to the block. This can be used if the block needs to access instance variables.

    class Thing
    end
    Thing.class_exec{
      def hello() "Hello there!" end
    }
    puts Thing.new.hello()

produces:

    Hello there!

    VALUE
    rb_mod_module_exec(int argc, const VALUE *argv, VALUE mod)
    {
        return yield_under(mod, mod, argc, argv);
    }

name → string click to toggle source

Returns the name of the module mod. Returns nil for anonymous modules.

    VALUE
    rb_mod_name(VALUE mod)
    {
        int permanent;
        VALUE path = classname(mod, &permanent);

        if (!NIL_P(path)) return rb_str_dup(path);
        return path;
    }

prepend(module, ...) → self click to toggle source

Invokes `Module.prepend_features` on each parameter in reverse order.

    static VALUE
    rb_mod_prepend(int argc, VALUE *argv, VALUE module)
    {
        int i;
        ID id_prepend_features, id_prepended;

        CONST_ID(id_prepend_features, "prepend_features");
        CONST_ID(id_prepended, "prepended");

        rb_check_arity(argc, 1, UNLIMITED_ARGUMENTS);
        for (i = 0; i < argc; i++)
            Check_Type(argv[i], T_MODULE);
        while (argc--) {
            rb_funcall(argv[argc], id_prepend_features, 1, module);
            rb_funcall(argv[argc], id_prepended, 1, module);
        }
        return module;
    }

private_class_method(symbol, ...) → mod click to toggle source
private_class_method(string, ...) → mod

Makes existing class methods private. Often used to hide the default constructor `new`.

String arguments are converted to symbols.

    class SimpleSingleton  # Not thread safe
      private_class_method :new
      def SimpleSingleton.create(*args, &block)
        @me = new(*args, &block) if ! @me
        @me
      end
    end

    static VALUE
    rb_mod_private_method(int argc, VALUE *argv, VALUE obj)
    {
        set_method_visibility(rb_singleton_class(obj), argc, argv, METHOD_VISI_PRIVATE);
        return obj;
    }

private_constant(symbol, ...) → mod click to toggle source

Makes a list of existing constants private.

    VALUE
    rb_mod_private_constant(int argc, const VALUE *argv, VALUE obj)
    {
        set_const_visibility(obj, argc, argv, CONST_PRIVATE, CONST_VISIBILITY_MASK);
        return obj;
    }

private_instance_methods(include_super=true) → array click to toggle source

Returns a list of the private instance methods defined in mod. If the optional parameter is `false`, the methods of any ancestors are not included.

    module Mod
      def method1()  end
      private :method1
      def method2()  end
    end
    Mod.instance_methods           #=> [:method2]
    Mod.private_instance_methods   #=> [:method1]

    VALUE
    rb_class_private_instance_methods(int argc, const VALUE *argv, VALUE mod)
    {
        return class_instance_method_list(argc, argv, mod, 0, ins_methods_priv_i);
    }

private_method_defined?(symbol) → true or false click to toggle source
private_method_defined?(string) → true or false

Returns `true` if the named private method is defined by _ mod_ (or its included modules and, if mod is a class, its ancestors). String arguments are converted to symbols.

    module A
      def method1()  end
    end
    class B
      private
      def method2()  end
    end
    class C < B
      include A
      def method3()  end
    end

    A.method_defined? :method1            #=> true
    C.private_method_defined? "method1"   #=> false
    C.private_method_defined? "method2"   #=> true
    C.method_defined? "method2"           #=> false

    static VALUE
    rb_mod_private_method_defined(VALUE mod, VALUE mid)
    {
        return check_definition(mod, mid, METHOD_VISI_PRIVATE);
    }

protected_instance_methods(include_super=true) → array click to toggle source

Returns a list of the protected instance methods defined in mod. If the optional parameter is `false`, the methods of any ancestors are not included.

    VALUE
    rb_class_protected_instance_methods(int argc, const VALUE *argv, VALUE mod)
    {
        return class_instance_method_list(argc, argv, mod, 0, ins_methods_prot_i);
    }

protected_method_defined?(symbol) → true or false click to toggle source
protected_method_defined?(string) → true or false

Returns `true` if the named protected method is defined by mod (or its included modules and, if mod is a class, its ancestors). String arguments are converted to symbols.

    module A
      def method1()  end
    end
    class B
      protected
      def method2()  end
    end
    class C < B
      include A
      def method3()  end
    end

    A.method_defined? :method1              #=> true
    C.protected_method_defined? "method1"   #=> false
    C.protected_method_defined? "method2"   #=> true
    C.method_defined? "method2"             #=> true

    static VALUE
    rb_mod_protected_method_defined(VALUE mod, VALUE mid)
    {
        return check_definition(mod, mid, METHOD_VISI_PROTECTED);
    }

public_class_method(symbol, ...) → mod click to toggle source
public_class_method(string, ...) → mod

Makes a list of existing class methods public.

String arguments are converted to symbols.

    static VALUE
    rb_mod_public_method(int argc, VALUE *argv, VALUE obj)
    {
        set_method_visibility(rb_singleton_class(obj), argc, argv, METHOD_VISI_PUBLIC);
        return obj;
    }

public_constant(symbol, ...) → mod click to toggle source

Makes a list of existing constants public.

    VALUE
    rb_mod_public_constant(int argc, const VALUE *argv, VALUE obj)
    {
        set_const_visibility(obj, argc, argv, CONST_PUBLIC, CONST_VISIBILITY_MASK);
        return obj;
    }

public_instance_method(symbol) → unbound_method click to toggle source

Similar to instance_method, searches public method only.

    static VALUE
    rb_mod_public_instance_method(VALUE mod, VALUE vid)
    {
        ID id = rb_check_id(&vid);
        if (!id) {
            rb_method_name_error(mod, vid);
        }
        return mnew(mod, Qundef, id, rb_cUnboundMethod, TRUE);
    }

public_instance_methods(include_super=true) → array click to toggle source

Returns a list of the public instance methods defined in mod. If the optional parameter is `false`, the methods of any ancestors are not included.

    VALUE
    rb_class_public_instance_methods(int argc, const VALUE *argv, VALUE mod)
    {
        return class_instance_method_list(argc, argv, mod, 0, ins_methods_pub_i);
    }

public_method_defined?(symbol) → true or false click to toggle source
public_method_defined?(string) → true or false

Returns `true` if the named public method is defined by mod (or its included modules and, if mod is a class, its ancestors). String arguments are converted to symbols.

    module A
      def method1()  end
    end
    class B
      protected
      def method2()  end
    end
    class C < B
      include A
      def method3()  end
    end

    A.method_defined? :method1           #=> true
    C.public_method_defined? "method1"   #=> true
    C.public_method_defined? "method2"   #=> false
    C.method_defined? "method2"          #=> true

    static VALUE
    rb_mod_public_method_defined(VALUE mod, VALUE mid)
    {
        return check_definition(mod, mid, METHOD_VISI_PUBLIC);
    }

remove_class_variable(sym) → obj click to toggle source

Removes the definition of the sym, returning that constant's value.

    class Dummy
      @@var = 99
      puts @@var
      remove_class_variable(:@@var)
      p(defined? @@var)
    end

produces:

    99
    nil

    VALUE
    rb_mod_remove_cvar(VALUE mod, VALUE name)
    {
        const ID id = id_for_var_message(mod, name, class, "wrong class variable name %1$s");
        st_data_t val, n = id;

        if (!id) {
          not_defined:
    	rb_name_err_raise("class variable %1$s not defined for %2$s",
    			  mod, name);
        }
        rb_check_frozen(mod);
        if (RCLASS_IV_TBL(mod) && st_delete(RCLASS_IV_TBL(mod), &n, &val)) {
    	return (VALUE)val;
        }
        if (rb_cvar_defined(mod, id)) {
    	rb_name_err_raise("cannot remove %1$s for %2$s", mod, ID2SYM(id));
        }
        goto not_defined;
    }

remove_method(symbol) → self click to toggle source
remove_method(string) → self

Removes the method identified by symbol from the current class. For an example, see `Module.undef_method`. String arguments are converted to symbols.

    static VALUE
    rb_mod_remove_method(int argc, VALUE *argv, VALUE mod)
    {
        int i;

        for (i = 0; i < argc; i++) {
            VALUE v = argv[i];
            ID id = rb_check_id(&v);
            if (!id) {
                rb_name_err_raise("method `%1$s' not defined in %2$s",
                                  mod, v);
            }
            remove_method(mod, id);
        }
        return mod;
    }

singleton_class? → true or false click to toggle source

Returns `true` if mod is a singleton class or `false` if it is an ordinary class or module.

    class C
    end
    C.singleton_class?                  #=> false
    C.singleton_class.singleton_class?  #=> true

    static VALUE
    rb_mod_singleton_p(VALUE klass)
    {
        if (RB_TYPE_P(klass, T_CLASS) && FL_TEST(klass, FL_SINGLETON))
            return Qtrue;
        return Qfalse;
    }

to_s → string click to toggle source

Returns a string representing this module or class. For basic classes and modules, this is the name. For singletons, we show information on the thing we're attached to as well.

    static VALUE
    rb_mod_to_s(VALUE klass)
    {
        ID id_defined_at;
        VALUE refined_class, defined_at;

        if (FL_TEST(klass, FL_SINGLETON)) {
            VALUE s = rb_usascii_str_new2("#<Class:");
            VALUE v = rb_ivar_get(klass, id__attached__);

            if (CLASS_OR_MODULE_P(v)) {
                rb_str_append(s, rb_inspect(v));
            }
            else {
                rb_str_append(s, rb_any_to_s(v));
            }
            rb_str_cat2(s, ">");

            return s;
        }
        refined_class = rb_refinement_module_get_refined_class(klass);
        if (!NIL_P(refined_class)) {
            VALUE s = rb_usascii_str_new2("#<refinement:");

            rb_str_concat(s, rb_inspect(refined_class));
            rb_str_cat2(s, "@");
            CONST_ID(id_defined_at, "__defined_at__");
            defined_at = rb_attr_get(klass, id_defined_at);
            rb_str_concat(s, rb_inspect(defined_at));
            rb_str_cat2(s, ">");
            return s;
        }
        return rb_str_dup(rb_class_name(klass));
    }

Also aliased as: inspect
undef_method(symbol) → self click to toggle source
undef_method(string) → self

Prevents the current class from responding to calls to the named method. Contrast this with `remove_method`, which deletes the method from the particular class; Ruby will still search superclasses and mixed-in modules for a possible receiver. String arguments are converted to symbols.

    class Parent
      def hello
        puts "In parent"
      end
    end
    class Child < Parent
      def hello
        puts "In child"
      end
    end

    c = Child.new
    c.hello

    class Child
      remove_method :hello  # remove from child, still in parent
    end
    c.hello

    class Child
      undef_method :hello   # prevent any calls to 'hello'
    end
    c.hello

produces:

    In child
    In parent
    prog.rb:23: undefined method `hello' for #<Child:0x401b3bb4> (NoMethodError)

    static VALUE
    rb_mod_undef_method(int argc, VALUE *argv, VALUE mod)
    {
        int i;
        for (i = 0; i < argc; i++) {
            VALUE v = argv[i];
            ID id = rb_check_id(&v);
            if (!id) {
                rb_method_name_error(mod, v);
            }
            rb_undef(mod, id);
        }
        return mod;
    }

### Private Instance Methods

append_features(mod) → mod click to toggle source

When this module is included in another, Ruby calls `append_features` in this module, passing it the receiving module in mod. Ruby's default implementation is to add the constants, methods, and module variables of this module to mod if this module has not already been added to mod or one of its ancestors. See also `Module#include`.

    static VALUE
    rb_mod_append_features(VALUE module, VALUE include)
    {
        if (!CLASS_OR_MODULE_P(include)) {
            Check_Type(include, T_CLASS);
        }
        rb_include_module(include, module);

        return module;
    }

extend_object(obj) → obj click to toggle source

Extends the specified object by adding this module's constants and methods (which are added as singleton methods). This is the callback method used by `Object#extend`.

    module Picky
      def Picky.extend_object(o)
        if String === o
          puts "Can't add Picky to a String"
        else
          puts "Picky added to #{o.class}"
          super
        end
      end
    end
    (s = Array.new).extend Picky  # Call Object.extend
    (s = "quick brown fox").extend Picky

produces:

    Picky added to Array
    Can't add Picky to a String

    static VALUE
    rb_mod_extend_object(VALUE mod, VALUE obj)
    {
        rb_extend_object(obj, mod);
        return obj;
    }

extended(othermod) click to toggle source

The equivalent of `included`, but for extended modules.

    module A
      def self.extended(mod)
        puts "#{self} extended in #{mod}"
      end
    end
    module Enumerable
      extend A
    end
     # => prints "A extended in Enumerable"

    static VALUE
    rb_obj_dummy(void)
    {
        return Qnil;
    }

included(othermod) click to toggle source

Callback invoked whenever the receiver is included in another module or class. This should be used in preference to `Module.append_features` if your code wants to perform some action when a module is included in another.

    module A
      def A.included(mod)
        puts "#{self} included in #{mod}"
      end
    end
    module Enumerable
      include A
    end
     # => prints "A included in Enumerable"

    static VALUE
    rb_obj_dummy(void)
    {
        return Qnil;
    }

method_added(method_name) click to toggle source

Invoked as a callback whenever an instance method is added to the receiver.

    module Chatty
      def self.method_added(method_name)
        puts "Adding #{method_name.inspect}"
      end
      def self.some_class_method() end
      def some_instance_method() end
    end

produces:

    Adding :some_instance_method

    static VALUE
    rb_obj_dummy(void)
    {
        return Qnil;
    }

method_removed(method_name) click to toggle source

Invoked as a callback whenever an instance method is removed from the receiver.

    module Chatty
      def self.method_removed(method_name)
        puts "Removing #{method_name.inspect}"
      end
      def self.some_class_method() end
      def some_instance_method() end
      class << self
        remove_method :some_class_method
      end
      remove_method :some_instance_method
    end

produces:

    Removing :some_instance_method

    static VALUE
    rb_obj_dummy(void)
    {
        return Qnil;
    }

method_undefined(p1) click to toggle source

Not documented

    static VALUE
    rb_obj_dummy(void)
    {
        return Qnil;
    }

module_function(symbol, ...) → self click to toggle source
module_function(string, ...) → self

Creates module functions for the named methods. These functions may be called with the module as a receiver, and also become available as instance methods to classes that mix in the module. Module functions are copies of the original, and so may be changed independently. The instance-method versions are made private. If used with no arguments, subsequently defined methods become module functions. String arguments are converted to symbols.

    module Mod
      def one
        "This is one"
      end
      module_function :one
    end
    class Cls
      include Mod
      def call_one
        one
      end
    end
    Mod.one     #=> "This is one"
    c = Cls.new
    c.call_one  #=> "This is one"
    module Mod
      def one
        "This is the new one"
      end
    end
    Mod.one     #=> "This is one"
    c.call_one  #=> "This is the new one"

    static VALUE
    rb_mod_modfunc(int argc, VALUE *argv, VALUE module)
    {
        int i;
        ID id;
        const rb_method_entry_t *me;

        if (!RB_TYPE_P(module, T_MODULE)) {
            rb_raise(rb_eTypeError, "module_function must be called for modules");
        }

        if (argc == 0) {
            rb_scope_module_func_set();
            return module;
        }

        set_method_visibility(module, argc, argv, METHOD_VISI_PRIVATE);

        for (i = 0; i < argc; i++) {
            VALUE m = module;

            id = rb_to_id(argv[i]);
            for (;;) {
                me = search_method(m, id, 0);
                if (me == 0) {
                    me = search_method(rb_cObject, id, 0);
                }
                if (UNDEFINED_METHOD_ENTRY_P(me)) {
                    rb_print_undef(module, id, METHOD_VISI_UNDEF);
                }
                if (me->def->type != VM_METHOD_TYPE_ZSUPER) {
                    break; /* normal case: need not to follow 'super' link */
                }
                m = RCLASS_SUPER(m);
                if (!m)
                    break;
            }
            rb_method_entry_set(rb_singleton_class(module), id, me, METHOD_VISI_PUBLIC);
        }
        return module;
    }

prepend_features(mod) → mod click to toggle source

When this module is prepended in another, Ruby calls `prepend_features` in this module, passing it the receiving module in mod. Ruby's default implementation is to overlay the constants, methods, and module variables of this module to mod if this module has not already been added to mod or one of its ancestors. See also `Module#prepend`.

    static VALUE
    rb_mod_prepend_features(VALUE module, VALUE prepend)
    {
        if (!CLASS_OR_MODULE_P(prepend)) {
            Check_Type(prepend, T_CLASS);
        }
        rb_prepend_module(prepend, module);

        return module;
    }

prepended(othermod) click to toggle source

The equivalent of `included`, but for prepended modules.

    module A
      def self.prepended(mod)
        puts "#{self} prepended to #{mod}"
      end
    end
    module Enumerable
      prepend A
    end
     # => prints "A prepended to Enumerable"

    static VALUE
    rb_obj_dummy(void)
    {
        return Qnil;
    }

private → self click to toggle source
private(symbol, ...) → self
private(string, ...) → self

With no arguments, sets the default visibility for subsequently defined methods to private. With arguments, sets the named methods to have private visibility. String arguments are converted to symbols.

    module Mod
      def a()  end
      def b()  end
      private
      def c()  end
      private :a
    end
    Mod.private_instance_methods   #=> [:a, :c]

Note that to show a private method on RDoc, use `:doc:`.

    static VALUE
    rb_mod_private(int argc, VALUE *argv, VALUE module)
    {
        return set_visibility(argc, argv, module, METHOD_VISI_PRIVATE);
    }

protected → self click to toggle source
protected(symbol, ...) → self
protected(string, ...) → self

With no arguments, sets the default visibility for subsequently defined methods to protected. With arguments, sets the named methods to have protected visibility. String arguments are converted to symbols.

If a method has protected visibility, it is callable only where `self` of the context is the same as the method. (method definition or instance_eval). This behavior is different from Java's protected method. Usually `private` should be used.

Note that a protected method is slow because it can't use inline cache.

To show a private method on RDoc, use `:doc:` instead of this.

    static VALUE
    rb_mod_protected(int argc, VALUE *argv, VALUE module)
    {
        return set_visibility(argc, argv, module, METHOD_VISI_PROTECTED);
    }

public → self click to toggle source
public(symbol, ...) → self
public(string, ...) → self

With no arguments, sets the default visibility for subsequently defined methods to public. With arguments, sets the named methods to have public visibility. String arguments are converted to symbols.

    static VALUE
    rb_mod_public(int argc, VALUE *argv, VALUE module)
    {
        return set_visibility(argc, argv, module, METHOD_VISI_PUBLIC);
    }

refine(mod) { block } → module click to toggle source

Refine mod in the receiver.

Returns a module, where refined methods are defined.

    static VALUE
    rb_mod_refine(VALUE module, VALUE klass)
    {
        VALUE refinement;
        ID id_refinements, id_activated_refinements,
           id_refined_class, id_defined_at;
        VALUE refinements, activated_refinements;
        rb_thread_t *th = GET_THREAD();
        VALUE block_handler = rb_vm_frame_block_handler(th->ec->cfp);

        if (block_handler == VM_BLOCK_HANDLER_NONE) {
            rb_raise(rb_eArgError, "no block given");
        }
        if (vm_block_handler_type(block_handler) != block_handler_type_iseq) {
            rb_raise(rb_eArgError, "can't pass a Proc as a block to Module#refine");
        }

        ensure_class_or_module(klass);
        CONST_ID(id_refinements, "__refinements__");
        refinements = rb_attr_get(module, id_refinements);
        if (NIL_P(refinements)) {
            refinements = hidden_identity_hash_new();
            rb_ivar_set(module, id_refinements, refinements);
        }
        CONST_ID(id_activated_refinements, "__activated_refinements__");
        activated_refinements = rb_attr_get(module, id_activated_refinements);
        if (NIL_P(activated_refinements)) {
            activated_refinements = hidden_identity_hash_new();
            rb_ivar_set(module, id_activated_refinements,
                        activated_refinements);
        }
        refinement = rb_hash_lookup(refinements, klass);
        if (NIL_P(refinement)) {
            VALUE superclass = refinement_superclass(klass);
            refinement = rb_module_new();
            RCLASS_SET_SUPER(refinement, superclass);
            FL_SET(refinement, RMODULE_IS_REFINEMENT);
            CONST_ID(id_refined_class, "__refined_class__");
            rb_ivar_set(refinement, id_refined_class, klass);
            CONST_ID(id_defined_at, "__defined_at__");
            rb_ivar_set(refinement, id_defined_at, module);
            rb_hash_aset(refinements, klass, refinement);
            add_activated_refinement(activated_refinements, klass, refinement);
        }
        rb_yield_refine_block(refinement, activated_refinements);
        return refinement;
    }

remove_const(sym) → obj click to toggle source

Removes the definition of the given constant, returning that constant's previous value. If that constant referred to a module, this will not change that module's name and can lead to confusion.

    VALUE
    rb_mod_remove_const(VALUE mod, VALUE name)
    {
        const ID id = id_for_var(mod, name, a, constant);

        if (!id) {
    	rb_name_err_raise("constant %2$s::%1$s not defined",
    			  mod, name);
        }
        return rb_const_remove(mod, id);
    }

using(module) → self click to toggle source

Import class refinements from module into the current class or module definition.

    static VALUE
    mod_using(VALUE self, VALUE module)
    {
        rb_control_frame_t *prev_cfp = previous_frame(GET_EC());

        if (prev_frame_func()) {
            rb_raise(rb_eRuntimeError,
                     "Module#using is not permitted in methods");
        }
        if (prev_cfp && prev_cfp->self != self) {
            rb_raise(rb_eRuntimeError, "Module#using is not called on self");
        }
        if (rb_block_given_p()) {
            ignored_block(module, "Module#");
        }
        rb_using_module(rb_vm_cref_replace_with_duplicated_cref(), module);
        return self;
    }