Trans
12/5/2006 3:08:00 AM
I have need for a general purpose simple namespace construction. Not
selector namespaces, mind you, just a method namespace. I made the
following attempt. So close! But it fails b/c if a method is already
defined in the class and the namespace module being added also has a
method of the same name they will clash. I worked around it by aliasing
the method with a temporary name then realiasing it to the original
name. This words EXCEPT when super is called in the method (see the
test case a the bottom).
Anone have any better ways of implementing?
Thanks,
T.
# namespace.rb
require 'facet/functor'
require 'facet/module/basename'
class Module
# Define a simple namespace.
#
# class A
# attr_writer :x
# namespace :inside do
# def x; @x; end
# end
# end
#
# a = A.new
# a.x = 10
# a.inside.x #=> 10
# a.x # no method error
def namespace( mod, &blk )
# If block is given then create a module, othewise
# get the name of the module.
if block_given?
name = mod.to_s
mod = Module.new(&blk)
else
name = mod.basename.downcase
mod = mod.dup
end
# We have to work around name clashes.
nameclashes = mod.instance_methods & instance_methods
nameclashes.each do |n|
alias_method "#{n}:namespace", n
end
# Include the module. This is neccessary, otherwise
# Ruby won't let us bind the instance methods.
include mod
# Undefine the instance methods of the module.
mod.instance_methods.each{ |m| undef_method m }
# Redefine the methods that clashed.
nameclashes.each do |n|
alias_method n, "#{n}:namespace"
undef_method "#{n}:namespace"
end
# Add a method for the namespace that delegates
# via the Functor to the module instance methods.
define_method(name) do
Functor.new(mod) do |op, base, *args|
base.instance_method(op).bind(self).call(*args)
end
end
end
end
# begin test
require 'test/unit'
class TestNamespace1 < Test::Unit::TestCase
module M
def x; "x"; end
end
class C
namespace M
end
def test_01
c = C.new
assert_equal('x', c.m.x)
end
def test_02
c = C.new
assert_raises(NoMethodError){ c.x }
end
end
class TestNamespace2 < Test::Unit::TestCase
class B
def x; 1; end
end
class C < B
def x; super; end
namespace :m do
def x; "x"; end
end
end
def test_01
c = C.new
assert_equal('x', c.m.x)
end
# THIS FAILS !!!
def test_02
c = C.new
assert_equal(1, c.x)
end
end