Here's a quick question for the Meta-programming gurus start with class A def self.method_a puts "A" end end How would I override method_a in such a way that the original method_a could be called at the end? sort of like that way you can call 'super' from a subclass. _Kevin
on 2006-04-19 20:50
on 2006-04-19 20:56
super still works: irb(main):001:0> class A irb(main):002:1> def self.method_a irb(main):003:2> puts "A" irb(main):004:2> end irb(main):005:1> end => nil irb(main):006:0> class NewA < A irb(main):007:1> def self.method_a irb(main):008:2> puts "NewA" irb(main):009:2> super irb(main):010:2> end irb(main):011:1> end => nil irb(main):012:0> NewA.method_a NewA A Farrel
on 2006-04-19 21:02
Oh wait I think I misunderstood the question are you looking to overwrite it in the same class?
on 2006-04-19 21:09
I'm not a guru, but the following works for me, though it is not very elegant: class A def self.method_a puts "A" end end class A @@old_method_a = self.method(:method_a) def self.method_a puts "B" @@old_method_a.call end end A.method_a # outputs "B", then "A" - Jake McArthur
on 2006-04-19 21:30
Yeah, not looking to subclass. On Thursday, April 20, 2006, at 3:59 AM, Farrel Lifson wrote: >Oh wait I think I misunderstood the question are you looking to >overwrite it in the same >class? > _Kevin
on 2006-04-19 21:52
On 4/19/06, Kevin Olbrich <email@example.com> wrote: > Yeah, not looking to subclass. class A def self.meth_a puts "one" end end class A class << self; alias meth_a_old meth_a end def self.meth_a meth_a_old puts "two" end end Though I personally think use of alias for this sort of thing as a "hack" (just my opinion of course). Another technique is to use a lexical closure: class A def self.meth_a puts "one" end end class A old_a = method(:meth_a) # The ugly part. This usually is nicer for instance methods. # You could write this a few different ways but they are all # ugly. Possibly something to factor out as a method. sclass = class << self; self end sclass.send :define_method, :meth_a do old_a.call puts "two" end end Both are messy but one is less likely to collide or cause problems with other code (not to mention littering the class with aliases). Brian.
on 2006-04-19 23:04
Thanks! I am slowly but surely getting the hang of this metaprogramming thing. On Thursday, April 20, 2006, at 4:49 AM, Brian Mitchell wrote: > class << self; alias meth_a_old meth_a end >class A > sclass = class << self; self end > _Kevin