instance method `alias_method_chain`

Ruby on Rails 4.2.9

Since v3.0.20 Last seen in v4.2.9

Available in: v3.0.20 v3.1.12 v3.2.22.5 v4.0.13 v4.1.16 v4.2.9

Compare with:

alias_method_chain(target, feature)

Encapsulates the common pattern of:

alias_method :foo_without_feature, :foo
alias_method :foo, :foo_with_feature

With this, you simply do:

alias_method_chain :foo, :feature

And both aliases are set up for you.

Query and bang methods (foo?, foo!) keep the same punctuation:

alias_method_chain :foo?, :feature

is equivalent to

alias_method :foo_without_feature?, :foo?
alias_method :foo?, :foo_with_feature?

so you can safely chain foo, foo?, foo! and/or foo= with the same feature.

Parameters

target req
feature req

Source

# File activesupport/lib/active_support/core_ext/module/aliasing.rb, line 23
  def alias_method_chain(target, feature)
    # Strip out punctuation on predicates, bang or writer methods since
    # e.g. target?_without_feature is not a valid method name.
    aliased_target, punctuation = target.to_s.sub(/([?!=])$/, ''), $1
    yield(aliased_target, punctuation) if block_given?

    with_method = "#{aliased_target}_with_#{feature}#{punctuation}"
    without_method = "#{aliased_target}_without_#{feature}#{punctuation}"

    alias_method without_method, target
    alias_method target, with_method

    case
    when public_method_defined?(without_method)
      public target
    when protected_method_defined?(without_method)
      protected target
    when private_method_defined?(without_method)
      private target
    end
  end

Defined in activesupport/lib/active_support/core_ext/module/aliasing.rb line 23 · View on GitHub · Improve this page · Find usages on GitHub

Defined in Module

Signature

Parameters