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
|
#!/usr/bin/env ruby
#--
# Copyright 2004, 2006 by Jim Weirich (jim@weirichhouse.org).
# All rights reserved.
# Permission is granted for use, copying, modification, distribution,
# and distribution of modified versions of this work as long as the
# above copyright notice is included.
#++
######################################################################
# BlankSlate provides an abstract base class with no predefined
# methods (except for <tt>\_\_send__</tt> and <tt>\_\_id__</tt>).
# BlankSlate is useful as a base class when writing classes that
# depend upon <tt>method_missing</tt> (e.g. dynamic proxies).
#
class BlankSlate
class << self
# Hide the method named +name+ in the BlankSlate class. Don't
# hide +instance_eval+ or any method beginning with "__".
def hide(name)
if instance_methods.include?(name.to_s) and
name !~ /^(__|instance_eval)/
@hidden_methods ||= {}
@hidden_methods[name.to_sym] = instance_method(name)
undef_method name
end
end
def find_hidden_method(name)
@hidden_methods ||= {}
@hidden_methods[name] || superclass.find_hidden_method(name)
end
# Redefine a previously hidden method so that it may be called on a blank
# slate object.
def reveal(name)
bound_method = nil
unbound_method = find_hidden_method(name)
fail "Don't know how to reveal method '#{name}'" unless unbound_method
define_method(name) do |*args|
bound_method ||= unbound_method.bind(self)
bound_method.call(*args)
end
end
end
instance_methods.each { |m| hide(m) }
end
######################################################################
# Since Ruby is very dynamic, methods added to the ancestors of
# BlankSlate <em>after BlankSlate is defined</em> will show up in the
# list of available BlankSlate methods. We handle this by defining a
# hook in the Object and Kernel classes that will hide any method
# defined after BlankSlate has been loaded.
#
module Kernel
class << self
alias_method :blank_slate_method_added, :method_added
# Detect method additions to Kernel and remove them in the
# BlankSlate class.
def method_added(name)
result = blank_slate_method_added(name)
return result if self != Kernel
BlankSlate.hide(name)
result
end
end
end
######################################################################
# Same as above, except in Object.
#
class Object
class << self
alias_method :blank_slate_method_added, :method_added
# Detect method additions to Object and remove them in the
# BlankSlate class.
def method_added(name)
result = blank_slate_method_added(name)
return result if self != Object
BlankSlate.hide(name)
result
end
def find_hidden_method(name)
nil
end
end
end
######################################################################
# Also, modules included into Object need to be scanned and have their
# instance methods removed from blank slate. In theory, modules
# included into Kernel would have to be removed as well, but a
# "feature" of Ruby prevents late includes into modules from being
# exposed in the first place.
#
class Module
alias blankslate_original_append_features append_features
def append_features(mod)
result = blankslate_original_append_features(mod)
return result if mod != Object
instance_methods.each do |name|
BlankSlate.hide(name)
end
result
end
end
|
