Referring to method in enclosing class

Ruby
1

I need to do something like what is being attempted in the code below.

The commented out code is what I can’t figure out: how do methods in a
nested classes call methods in their enclosing class? Is this even
possible?

class Enclosing
def go
Hello.new.do_say_hello
end

def say_hello
“Hello World!”
end

class Hello
def do_say_hello

puts Enclosing class’s say_hello method

end

end

end

2

On Jan 30, 2008, at 8:42 PM, Richard E. wrote:

end
This doesn’t really make sense. First of all nested classes are just
a way to organize the names of classes. The nesting is completely
orthogonal to the inheritance hierarchy. In your example,
Enclosing and Enclosing::Hello are only related by their name.
Neither one is a subclass or parent of the other, they are both
subclasses of Object.

The second issue is that those are instance methods so you’ll need an
instance of Enclosing and and instance of Hello before you can even
think of calling Hello#do_say_hello or Enclosing#say_hello.

I’m not sure what you are after but you kind of have two choices.
Make Hello a subclass of Enclosing, or make Enclosing a module and
include its methods into Hello. These examples below will ‘work’
but they are awkward at best. I’m not sure exactly what you are
trying to do so I’m not sure what to suggest instead.

Subclass:

class Enclosing
def go
Hello.new.do_say_hello
end

def say_hello
“Hello World!”
end

class Hello < Enclosing
def do_say_hello
puts say_hello
end
end

end

Enclosing.new.go

Module

module Enclosing
def go
Hello.new.do_say_hello
end

def say_hello
“Hello World!”
end

class Hello
include Enclosing
def do_say_hello
puts say_hello
end
end

end

Enclosing::Hello.new.go

3

Richard E. wrote:

I need to do something like what is being attempted in the code below.

The commented out code is what I can’t figure out: how do methods in a
nested classes call methods in their enclosing class? Is this even
possible?

class Enclosing
def go
Hello.new.do_say_hello
end

def say_hello
“Hello World!”
end

class Hello
def do_say_hello

puts Enclosing class’s say_hello method

end

end

end

Why do you want to nest Hello inside Enclosing?

class Enclosing
def say_hello
puts “hi”
end
end

class Hello
def initialize
@e = Enclosing.new
end

def do_say_hello
@e.say_hello
end
end

h = Hello.new
h.do_say_hello

–output:–
hi

4

Thanks for the reply.

I wanted to add functionality to the enclosing class via the addition of
the enclosed class with minimal changes to the enclosing class and its
methods. Specifically, the enclosed class is intended to subclass a
threading framework class and, after instantiated, call methods on the
enclosing class. The enclosing class already extends another class.

I come from a Java background if that helps explaining anything about my
approach to this.

Rich

Gary W. wrote:

On Jan 30, 2008, at 8:42 PM, Richard E. wrote:

end
This doesn’t really make sense. First of all nested classes are just
a way to organize the names of classes. The nesting is completely
orthogonal to the inheritance hierarchy. In your example,
Enclosing and Enclosing::Hello are only related by their name.
Neither one is a subclass or parent of the other, they are both
subclasses of Object.

The second issue is that those are instance methods so you’ll need an
instance of Enclosing and and instance of Hello before you can even
think of calling Hello#do_say_hello or Enclosing#say_hello.

I’m not sure what you are after but you kind of have two choices.
Make Hello a subclass of Enclosing, or make Enclosing a module and
include its methods into Hello. These examples below will ‘work’
but they are awkward at best. I’m not sure exactly what you are
trying to do so I’m not sure what to suggest instead.

Subclass:

class Enclosing
def go
Hello.new.do_say_hello
end

def say_hello
“Hello World!”
end

class Hello < Enclosing
def do_say_hello
puts say_hello
end
end

end

Enclosing.new.go

Module

module Enclosing
def go
Hello.new.do_say_hello
end

def say_hello
“Hello World!”
end

class Hello
include Enclosing
def do_say_hello
puts say_hello
end
end

end

Enclosing::Hello.new.go

5

Richard E. wrote:

I need to do something like what is being attempted in the code below.

The commented out code is what I can’t figure out: how do methods in a
nested classes call methods in their enclosing class? Is this even
possible?

class Enclosing
def go
Hello.new.do_say_hello
end

def say_hello
“Hello World!”
end

class Hello
def do_say_hello

puts Enclosing class’s say_hello method

end

end

end

Not to fear, I have used similar stuff in other languages … I believe
what you are looking for is delegates:

http://www.ruby-doc.org/stdlib/libdoc/delegate/rdoc/index.html

hth

ilan

6

On Jan 31, 3:23 pm, Richard E. [email protected] wrote:

Thanks for the reply.

I wanted to add functionality to the enclosing class via the addition of
the enclosed class with minimal changes to the enclosing class and its
methods. Specifically, the enclosed class is intended to subclass a
threading framework class and, after instantiated, call methods on the
enclosing class. The enclosing class already extends another class.

class Foo
def yay
puts “foo sez yay”
end

Creates a Foo::Bar class that is a subclass of Foo

class Bar < Foo
def yay
puts “bar sez yay”
super
puts “bar iz done”
end
end
end

Foo::Bar.new.yay
#=> bar sez yay
#=> foo sez yay
#=> bar iz done