From: transfire@...
Date: 2006-07-22T23:26:24+09:00
Subject: when I say method_defined? I mean it!

I've been bitten by this way too many times now. And I'm just plain
tired of it.

Today's case:

  def wrap_method( sym, &blk )
    raise ArgumentError, "method does not exist -- #{sym}" unless
method_defined?( sym )
    old = instance_method(sym)
    define_method(sym) { |*args| blk.call(old.bind(self), *args) }
  end

Seems all well and good until now when it comes out that
#method_defined?, like #instance_methods, does something only a Ruby
hacker without a life would expect. The actual _monster_ code needed
is:

def wrap_method( sym, &blk )
    unless public_method_defined?( sym ) || private_method_defined?(
sym ) || protected_method_defined?( sym )
      raise ArgumentError, "method does not exist -- #{sym}"
    end
    old = instance_method(sym)
    define_method(sym) { |*args| blk.call(old.bind(self), *args) }
  end

Now, it just doesn't stand to any good reason. When we wan't to
actually grab a method, we don't use #public_instance_method, do we?
That would be a nightmare! And so it is with the above case and many
others I've delt with. Every time I have to go back and fix this "bug"
recalling the terribly inconvenient and anti-literal definition of
these methods-methods.

T.