Help on inheritance and class methods pls?


#1

Hi there,

Hoping someone explain this to me as I’d like to understand it properly.
I’ve been reading about Ruby’s metaclasses, but I don’t get this:

class Test
def foo
puts “in foo”
end
end
=> nil

class Test2 < Test
def self.bar
foo
end
def method_missing(name, *args)
puts “in method_missing”
end
end
=> nil

Test2.new.bar
in method_missing
=> nil
Test2.new.foo
in foo
=> nil

why does invoking method bar on the instance find class Test2’s
method_missing instance method, but not instance method foo inherited
from class Test?

Thanks for any help!


#2

Hi –

On Fri, 17 Oct 2008, Barbara Mcinnes wrote:

=> nil

Test2.new.bar
in method_missing
=> nil
Test2.new.foo
in foo
=> nil

why does invoking method bar on the instance find class Test2’s
method_missing instance method, but not instance method foo inherited
from class Test?

You’ve got a class method Test2.bar, but you never call it. (The
program would run the same if you deleted that method.) When you send
the message ‘bar’ to your instance of Test2, it hits method_missing
because there’s no instance method bar in Test2 or any of its
ancestors.

David