Module: Amp::ModuleExtensions

Included in:
Plugins::Base
Defined in:
lib/amp-front/support/module_extensions.rb

Overview

These are extensions to Amp modules. This module should be extended by any Amp modules seeking to take advantage of them. This prevents conflicts with other libraries defining extensions of the same name.

Instance Method Summary collapse

Instance Method Details

#cattr_accessor(*attrs) ⇒ Object

Creates readers and writers for the given instance variables.



41
42
43
44
 
# File 'lib/amp-front/support/module_extensions.rb', line 41

def cattr_accessor(*attrs)
  cattr_reader(*attrs)
  cattr_writer(*attrs)
end

#cattr_accessor_with_default(attr, default) ⇒ Object 



46
47
48
49
50
51
52
53
54
55
56
57
58
59
 
# File 'lib/amp-front/support/module_extensions.rb', line 46

def cattr_accessor_with_default(attr, default)
  varname = "@#{attr}".to_sym
  singleton_class.instance_eval do
    define_method attr do
      if instance_variable_defined?(varname)
        instance_variable_get(varname)
      else
        instance_variable_set(varname, default)
        default
      end
    end
  end
  cattr_writer(attr)
end

#cattr_get_and_setter(*attrs) ⇒ Object

Creates a DSL-friendly set-and-getter method. The method, when called with no arguments, acts as a getter. When called with arguments, it acts as a setter. Uses class instance variables - this is not for generating instance methods.

Examples:

class A
  cattr_get_and_setter :type
end
class B < A
  type :silly
end
p B.type  # => :silly


74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
 
# File 'lib/amp-front/support/module_extensions.rb', line 74

def cattr_get_and_setter(*attrs)
  attrs.each do |attr|
    cattr_accessor attr
    singleton_class.instance_eval do
      alias_method "#{attr}_old_get".to_sym, attr
      define_method attr do |*args, &blk|
        if args.size > 0
          send("#{attr}=", *args)
        elsif blk != nil
          send("#{attr}=", blk)
        else
          send("#{attr}_old_get")
        end
      end
    end
  end
end

#cattr_reader(*attrs) ⇒ Object

Creates a reader for the given instance variables on the class object.



27
28
29
30
31
 
# File 'lib/amp-front/support/module_extensions.rb', line 27

def cattr_reader(*attrs)
  attrs.each do |attr|
    instance_eval("def #{attr}; @#{attr}; end")
  end
end

#cattr_writer(*attrs) ⇒ Object

Creates a writer for the given instance variables on the class object.



34
35
36
37
38
 
# File 'lib/amp-front/support/module_extensions.rb', line 34

def cattr_writer(*attrs)
  attrs.each do |attr|
    instance_eval("def #{attr}=(val); @#{attr} = val; end")
  end
end

#singleton_class ⇒ Object 



20
21
22
23
24
 
# File 'lib/amp-front/support/module_extensions.rb', line 20

def singleton_class
  class << self
    self
  end
end