1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
|
class Class
# Automatically create an initializer assigning the given
# arguments.
#
# class MyClass
# initializer(:a, "b", :c)
# end
#
# _is equivalent to_
#
# class MyClass
# def initialize(a, b, c)
# @a,@b,@c = a,b,c
# end
# end
#
# Downside: Initializers defined like this can't take blocks.
# This can be fixed when Ruby 1.9 is out.
#
# The initializer will not raise an Exception when the user
# does not supply a value for each instance variable. In that
# case it will just set the instance variable to nil. You can
# assign default values or raise an Exception in the block.
def initialize_on(*attributes, &block)
define_method(:initialize) do |*args|
attributes.zip(args) do |sym, value|
instance_variable_set("@#{sym}", value)
end
instance_eval(&block) if block
end
attributes
end
end
=begin test
require 'facets/class/initialize_on.rb'
require 'test/unit'
class TC_Class_Initializer < Test::Unit::TestCase
def test_initialize_on
cc = Class.new
cc.class_eval {
initialize_on :ai
attr_reader :ai
}
c = cc.new(10)
assert_equal( 10, c.ai )
end
end
=end
|
