# class Gem::DependencyList

`Gem::DependencyList` is used for installing and uninstalling gems in the correct order to avoid conflicts.

### Attributes

development [RW]

Allows enabling/disabling use of development dependencies

specs [R]

### Public Class Methods

from_specs ()
Source

    # File lib/rubygems/dependency_list.rb, line 34
    def self.from_specs
      list = new
      list.add(*Gem::Specification.to_a)
      list
    end

Creates a `DependencyList` from the current specs.

new (development = false)
Source

    # File lib/rubygems/dependency_list.rb, line 44
    def initialize(development = false)
      @specs = []

      @development = development
    end

Creates a new `DependencyList`. If `development` is true, development dependencies will be included.

### Public Instance Methods

add (*gemspecs)
Source

    # File lib/rubygems/dependency_list.rb, line 53
    def add(*gemspecs)
      @specs.concat gemspecs
    end

Adds `gemspecs` to the dependency list.

clear ()
Source

    # File lib/rubygems/dependency_list.rb, line 57
    def clear
      @specs.clear
    end

dependency_order ()
Source

    # File lib/rubygems/dependency_list.rb, line 76
    def dependency_order
      sorted = strongly_connected_components.flatten

      result = []
      seen = {}

      sorted.each do |spec|
        if index = seen[spec.name]
          if result[index].version < spec.version
            result[index] = spec
          end
        else
          seen[spec.name] = result.length
          result << spec
        end
      end

      result.reverse
    end

Return a list of the gem specifications in the dependency list, sorted in order so that no gemspec in the list depends on a gemspec earlier in the list.

This is useful when removing gems from a set of installed gems. By removing them in the returned order, you don’t get into as many dependency issues.

If there are circular dependencies (yuck!), then gems will be returned in order until only the circular dependents and anything they reference are left. Then arbitrary gemspecs will be returned until the circular dependency is broken, after which gems will be returned in dependency order again.

each (&block)
Source

    # File lib/rubygems/dependency_list.rb, line 99
    def each(&block)
      dependency_order.each(&block)
    end

Iterator over `dependency_order`

find_name (full_name)
Source

    # File lib/rubygems/dependency_list.rb, line 103
    def find_name(full_name)
      @specs.find {|spec| spec.full_name == full_name }
    end

ok? ()
Source

    # File lib/rubygems/dependency_list.rb, line 114
    def ok?
      why_not_ok?(:quick).empty?
    end

Are all the dependencies in the list satisfied?

ok_to_remove? (full_name, check_dev=true)
Source

    # File lib/rubygems/dependency_list.rb, line 143
    def ok_to_remove?(full_name, check_dev=true)
      gem_to_remove = find_name full_name

      # If the state is inconsistent, at least don't crash
      return true unless gem_to_remove

      siblings = @specs.find_all do |s|
        s.name == gem_to_remove.name &&
          s.full_name != gem_to_remove.full_name
      end

      deps = []

      @specs.each do |spec|
        check = check_dev ? spec.dependencies : spec.runtime_dependencies

        check.each do |dep|
          deps << dep if gem_to_remove.satisfies_requirement?(dep)
        end
      end

      deps.all? do |dep|
        siblings.any? do |s|
          s.satisfies_requirement? dep
        end
      end
    end

It is ok to remove a gemspec from the dependency list?

If removing the gemspec creates breaks a currently ok dependency, then it is NOT ok to remove the gemspec.

remove_by_name (full_name)
Source

    # File lib/rubygems/dependency_list.rb, line 186
    def remove_by_name(full_name)
      @specs.delete_if {|spec| spec.full_name == full_name }
    end

Removes the gemspec matching `full_name` from the dependency list

remove_specs_unsatisfied_by (dependencies)
Source

    # File lib/rubygems/dependency_list.rb, line 176
    def remove_specs_unsatisfied_by(dependencies)
      specs.reject! do |spec|
        dep = dependencies[spec.name]
        dep && !dep.requirement.satisfied_by?(spec.version)
      end
    end

Remove everything in the `DependencyList` that matches but doesn’t satisfy items in `dependencies` (a hash of gem names to arrays of dependencies).

spec_predecessors ()
Source

    # File lib/rubygems/dependency_list.rb, line 194
    def spec_predecessors
      result = Hash.new {|h,k| h[k] = [] }

      specs = @specs.sort.reverse

      specs.each do |spec|
        specs.each do |other|
          next if spec == other

          other.dependencies.each do |dep|
            if spec.satisfies_requirement? dep
              result[spec] << other
            end
          end
        end
      end

      result
    end

Return a hash of predecessors. `result[spec]` is an `Array` of gemspecs that have a dependency satisfied by the named gemspec.

tsort_each_child (node) { |spec| ... }
Source

    # File lib/rubygems/dependency_list.rb, line 218
    def tsort_each_child(node)
      specs = @specs.sort.reverse

      dependencies = node.runtime_dependencies
      dependencies.push(*node.development_dependencies) if @development

      dependencies.each do |dep|
        specs.each do |spec|
          if spec.satisfies_requirement? dep
            yield spec
            break
          end
        end
      end
    end

tsort_each_node (&block)
Source

    # File lib/rubygems/dependency_list.rb, line 214
    def tsort_each_node(&block)
      @specs.each(&block)
    end

why_not_ok? (quick = false)
Source

    # File lib/rubygems/dependency_list.rb, line 118
    def why_not_ok?(quick = false)
      unsatisfied = Hash.new {|h,k| h[k] = [] }
      each do |spec|
        spec.runtime_dependencies.each do |dep|
          inst = Gem::Specification.any? do |installed_spec|
            dep.name == installed_spec.name &&
              dep.requirement.satisfied_by?(installed_spec.version)
          end

          unless inst || @specs.find {|s| s.satisfies_requirement? dep }
            unsatisfied[spec.name] << dep
            return unsatisfied if quick
          end
        end
      end

      unsatisfied
    end

### Private Instance Methods

active_count (specs, ignored)
Source

    # File lib/rubygems/dependency_list.rb, line 240
    def active_count(specs, ignored)
      specs.count {|spec| ignored[spec.full_name].nil? }
    end

Count the number of gemspecs in the list `specs` that are not in `ignored`.