# 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() click to toggle source

Creates a `DependencyList` from the current specs.

    # File lib/rubygems/dependency_list.rb, line 33
    def self.from_specs
      list = new
      list.add(*Gem::Specification.to_a)
      list
    end

new(development = false) click to toggle source

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

    # File lib/rubygems/dependency_list.rb, line 43
    def initialize(development = false)
      @specs = []

      @development = development
    end

### Public Instance Methods

add(*gemspecs) click to toggle source

Adds `gemspecs` to the dependency list.

    # File lib/rubygems/dependency_list.rb, line 52
    def add(*gemspecs)
      @specs.concat gemspecs
    end

clear() click to toggle source

    # File lib/rubygems/dependency_list.rb, line 56
    def clear
      @specs.clear
    end

dependency_order() click to toggle source

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.

    # File lib/rubygems/dependency_list.rb, line 75
    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

each(&block) click to toggle source

Iterator over `dependency_order`

    # File lib/rubygems/dependency_list.rb, line 98
    def each(&block)
      dependency_order.each(&block)
    end

find_name(full_name) click to toggle source

    # File lib/rubygems/dependency_list.rb, line 102
    def find_name(full_name)
      @specs.find {|spec| spec.full_name == full_name }
    end

ok?() click to toggle source

Are all the dependencies in the list satisfied?

    # File lib/rubygems/dependency_list.rb, line 113
    def ok?
      why_not_ok?(:quick).empty?
    end

ok_to_remove?(full_name, check_dev=true) click to toggle source

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.

    # File lib/rubygems/dependency_list.rb, line 142
    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

remove_by_name(full_name) click to toggle source

Removes the gemspec matching `full_name` from the dependency list

    # File lib/rubygems/dependency_list.rb, line 185
    def remove_by_name(full_name)
      @specs.delete_if {|spec| spec.full_name == full_name }
    end

remove_specs_unsatisfied_by(dependencies) click to toggle source

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

    # File lib/rubygems/dependency_list.rb, line 175
    def remove_specs_unsatisfied_by(dependencies)
      specs.reject! do |spec|
        dep = dependencies[spec.name]
        dep && !dep.requirement.satisfied_by?(spec.version)
      end
    end

spec_predecessors() click to toggle source

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

    # File lib/rubygems/dependency_list.rb, line 193
    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

tsort_each_child(node) { |spec| ... } click to toggle source

    # File lib/rubygems/dependency_list.rb, line 217
    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) click to toggle source

    # File lib/rubygems/dependency_list.rb, line 213
    def tsort_each_node(&block)
      @specs.each(&block)
    end

why_not_ok?(quick = false) click to toggle source

    # File lib/rubygems/dependency_list.rb, line 117
    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) click to toggle source

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

    # File lib/rubygems/dependency_list.rb, line 239
    def active_count(specs, ignored)
      specs.count {|spec| ignored[spec.full_name].nil? }
    end