From: "Mauricio Fernández" <batsman.geo@...>
Date: 2004-04-18T00:23:49+09:00
Subject: prior method definition


This feels cleaner than the alias_method + redef. method trick, and I
haven't found anything similar in the archives.

It still suffers from the problem exposed in [ruby-talk:75334]. In
addition, blocks cannot be propagated but it will be possible once 
[ruby-talk:90671] is implemented (of course, by then we'll have real
advices, but still ;)

batsman@tux-chan:~/src$ cat aop2.rb

class Module
    def def_advice(meth, &block)
        prev = self.instance_method(meth)
        define_method(meth) do |*a|
            block.call prev.bind(self), *a
        end
    end

    def def_preadvice(meth, &block)
        prev = self.instance_method(meth)
        define_method(meth) do |*a|
            block.call(*a)
            prev.bind(self).call(*a)
        end
    end

    def def_postadvice(meth, &block)
        prev = self.instance_method(meth)
        define_method(meth) do |*a|
            prev.bind(self).call(*a)
            block.call(*a)
        end
    end
end

class A
    def foo(*a)
        puts "A#foo #{a.inspect}"
    end
end
a = A.new
a.foo

class A
    def_advice(:foo) do |prev, *a|
        puts "before"
        prev[*a]
        puts "after"
    end
end

puts "--"
a.foo

class A
    def_preadvice(:foo) { puts "pre 1" }
    def_postadvice(:foo) { puts "post 1"}
    def_preadvice(:foo) { puts "pre 2" }
end

puts "--"
a.foo
batsman@tux-chan:~/src$ ruby ao
aop.rb   aop2.rb
batsman@tux-chan:~/src$ ruby aop2.rb
A#foo []
--
before
A#foo []
after
--
pre 2
pre 1
before
A#foo []
after
post 1


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