Here’s a pattern you see a lot of in Ruby:
foo.bar if foo.respond_to?(:bar)
I do this kind of thing frequently, as I’m a big fan of ducktyping over checking an object’s class explicitly. I’m not concerned with the class of an object as long as it does what I’m asking.
Io has a nice and simple way of doing this, built into the language:
foo ?bar
If foo has slot bar (ie, in Rubyland it responds to bar), send the bar message to foo.
Simple trick: you can essentially bootstrap Ruby to do the same thing (note I use the word try in this example, which may have too much baggage for some of you):
class Object
def try(meth, *args, &block)
__send__(meth, *args, &block) if respond_to? meth
end
end
Then you can do foo.try :bar
If the object doesn’t respond to the method, nil is returned, as in Io.
