How to access a method in the parent class

Ruby
1

Hi, I’ll explain my problem with an example code:

module M
def hello
puts “hello !!!”
B.new
end

class B
def initialize
puts “B instance initialized !!!”
bye() <— ERROR !!!
end
end
end

class A
include M

def bye
puts “bye !!!”
end
end

a = A.new
a.hello

I want the following behaviour:

irb> a.hello
=> “hello !!!”
=> “B instance initialized !!!”
=> “bye !!!”

But the last bye() gives an error since, of course, “bye” is not defined
in B
class, but in A class.

I know that if it would be:

module M

def hello
puts “hello !!!”
bye
end

end

irb> a.hellp

This works since “bye()” calls the “bye” method in class A. But this is
not my
case.

How could I call A#bye method from M::B class?

Thanks a lot.

2

2008/9/9 Iñaki Baz C. [email protected]

           def initialize
   def bye

I want the following behaviour:

irb> a.hellp

This works since “bye()” calls the “bye” method in class A. But this is not
my
case.

How could I call A#bye method from M::B class?

Thanks a lot.

To call a method from another class in the context of an instance of B,
put
this inside M::B#initialize:

A.instance_method(:bye).bind(self).call()

Hard to tell from this code, seeing as how it does nothing apparently
useful, but if you find yourself doing this it may be a sign that you
need
to rethink your design.

3

Hi –

On Wed, 10 Sep 2008, James C. wrote:

   include M

B

Thanks a lot.

To call a method from another class in the context of an instance of B, put
this inside M::B#initialize:

A.instance_method(:bye).bind(self).call()

That won’t work here, because you’d need an instance of A (or a
subclass of A).

Hard to tell from this code, seeing as how it does nothing apparently
useful, but if you find yourself doing this it may be a sign that you need
to rethink your design.

It definitely looks a bit inside-out: A requires that M exist, but A
is essentially trying to serve as a superclass for M::B. Sort of like
this:

module M
def hello
puts “hello !!!”
B.new
end
end

class A
include M
def bye
puts “bye !!!”
end
end

module M
class B < A
def initialize
puts “B instance initialized !!!”
bye
end
end
end

which works, but does indeed look like it would need some ironing out
in the design.

David

4

El Miércoles, 10 de Septiembre de 2008, David A. Black escribió:

   puts “bye !!!”
end

which works, but does indeed look like it would need some ironing out
in the design.

Thanks a lot. Maybe I should re-desing the code to avoid using things so
exotic… :slight_smile:

Really thanks a lot to both.