Class: Module

Inherits:
Object show all
Defined in:
lib/inactive_support/core_ext/module/aliasing.rb

Instance Method Summary collapse

Instance Method Details

#alias_attribute(new_name, old_name) ⇒ Object

Allows you to make aliases for attributes, which includes getter, setter, and query methods.

Example:

class Content < ActiveRecord::Base
  # has a title attribute
end

class Email < Content
  alias_attribute :subject, :title
end

e = Email.find(1)
e.title    # => "Superstars"
e.subject  # => "Superstars"
e.subject? # => true
e.subject = "Megastars"
e.title    # => "Megastars"



63
64
65
66
67
68
69
 
# File 'lib/inactive_support/core_ext/module/aliasing.rb', line 63

def alias_attribute(new_name, old_name)
  module_eval <<-STR, __FILE__, __LINE__+1
    def #{new_name}; self.#{old_name}; end
    def #{new_name}?; self.#{old_name}?; end
    def #{new_name}=(v); self.#{old_name} = v; end
  STR
end

#alias_method_chain(target, feature) {|aliased_target, punctuation| ... } ⇒ Object

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?, and foo! with the same feature.

Yields:

  • (aliased_target, punctuation) 


23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
 
# File 'lib/inactive_support/core_ext/module/aliasing.rb', line 23

def alias_method_chain(target, feature)
  # Strip out punctuation on predicates or bang 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, without_method = "#{aliased_target}_with_#{feature}#{punctuation}", "#{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