# class RubyVM

for ast.c

The `RubyVM` module only exists on MRI. `RubyVM` is not defined in other Ruby implementations such as JRuby and TruffleRuby.

The `RubyVM` module provides some access to MRI internals. This module is for very limited purposes, such as debugging, prototyping, and research. Normal users must not use it. This module is not portable between Ruby implementations.

### Constants

DEFAULT_PARAMS

  `DEFAULT_PARAMS` This constant exposes the VM's default parameters. Note that changing these values does not affect VM execution. Specification is not stable and you should not depend on this value. Of course, this constant is MRI specific.

INSTRUCTION_NAMES

  `INSTRUCTION_NAMES` A list of bytecode instruction names in MRI. This constant is MRI specific.

OPTS

  `OPTS` An `Array` of VM build options. This constant is MRI specific.

### Public Class Methods

each_builtin() click to toggle source

    static VALUE
    each_builtin(VALUE self)
    {
        st_foreach(loaded_builtin_table, each_builtin_i, 0);
        return Qnil;
    }

stat → Hash click to toggle source
stat(hsh) → hsh
stat(Symbol) → Numeric

Returns a `Hash` containing implementation-dependent counters inside the VM.

This hash includes information about method/constant cache serials:

    {
      :global_method_state=>251,
      :global_constant_state=>481,
      :class_serial=>9029
    }

The contents of the hash are implementation specific and may be changed in the future.

This method is only expected to work on C Ruby.

    static VALUE
    vm_stat(int argc, VALUE *argv, VALUE self)
    {
        static VALUE sym_global_method_state, sym_global_constant_state, sym_class_serial;
        VALUE arg = Qnil;
        VALUE hash = Qnil, key = Qnil;

        if (rb_check_arity(argc, 0, 1) == 1) {
            arg = argv[0];
            if (SYMBOL_P(arg))
                key = arg;
            else if (RB_TYPE_P(arg, T_HASH))
                hash = arg;
            else
                rb_raise(rb_eTypeError, "non-hash or symbol given");
        }
        else {
            hash = rb_hash_new();
        }

        if (sym_global_method_state == 0) {
    #define S(s) sym_##s = ID2SYM(rb_intern_const(#s))
            S(global_method_state);
            S(global_constant_state);
            S(class_serial);
    #undef S
        }

    #define SET(name, attr) \
        if (key == sym_##name) \
            return SERIALT2NUM(attr); \
        else if (hash != Qnil) \
            rb_hash_aset(hash, sym_##name, SERIALT2NUM(attr));

        SET(global_method_state, ruby_vm_global_method_state);
        SET(global_constant_state, ruby_vm_global_constant_state);
        SET(class_serial, ruby_vm_class_serial);
    #undef SET

        if (!NIL_P(key)) { /* matched key should return above */
            rb_raise(rb_eArgError, "unknown key: %"PRIsVALUE, rb_sym2str(key));
        }

        return hash;
    }