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
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
|
# Delegation class that delegates even methods defined in super class,
# which can not be covered with normal method_missing hack.
#
# Delegator is the abstract delegation class. Need to redefine
# `__getobj__' method in the subclass. SimpleDelegator is the
# concrete subclass for simple delegation.
#
# Usage:
# foo = Object.new
# foo2 = SimpleDelegator.new(foo)
# foo.hash == foo2.hash # => true
#
# Foo = DelegateClass(Array)
#
# class ExtArray<DelegateClass(Array)
# ...
# end
class Delegator
def initialize(obj)
preserved = ::Kernel.instance_methods
for t in self.type.ancestors
preserved |= t.instance_methods
break if t == Delegator
end
preserved -= ["to_s","to_a","inspect","hash","eql?","==","=~","==="]
for method in obj.methods
next if preserved.include? method
eval <<EOS
def self.#{method}(*args, &block)
begin
__getobj__.__send__(:#{method}, *args, &block)
rescue Exception
n = if /:in `__getobj__'$/ =~ $@[0] then 1 else 2 end #`
$@[1,n] = nil
raise
end
end
EOS
end
end
def __getobj__
raise NotImplementError, "need to define `__getobj__'"
end
end
class SimpleDelegator<Delegator
def initialize(obj)
super
@obj = obj
end
def __getobj__
@obj
end
def __setobj__(obj)
@obj = obj
end
end
# backward compatibility ^_^;;;
Delegater = Delegator
SimpleDelegater = SimpleDelegator
#
def DelegateClass(superclass)
klass = Class.new
methods = superclass.instance_methods
methods -= ::Kernel.instance_methods
methods |= ["to_s","to_a","inspect","hash","eql?","==","=~","==="]
klass.module_eval <<EOS
def initialize(obj)
@obj = obj
end
EOS
for method in methods
klass.module_eval <<EOS
def #{method}(*args, &block)
begin
@obj.__send__(:#{method}, *args, &block)
rescue
$@[0,2] = nil
raise
end
end
EOS
end
return klass;
end
if __FILE__ == $0
class ExtArray<DelegateClass(Array)
def initialize()
super([])
end
end
ary = ExtArray.new
p ary.type
ary.push 25
p ary
foo = Object.new
def foo.test
raise 'this is OK'
end
foo2 = SimpleDelegator.new(foo)
p foo.hash == foo2.hash # => true
foo.test # raise error!
end
|