Using a class to extend a singleton?

Ruby
1

Given:

class X
def yo=x; @yo=x; end
end

class Y
def yo!; puts @yo; end
end

x = X.new

Is there any way to extend x with Y’s functionality (without going
back and changing the given code)? Eg.

x.yo=“Hello World”
x.yo!
Hello World

T.

2

On 01/03/2008, Trans [email protected] wrote:

x = X.new

Is there any way to extend x with Y’s functionality (without going
back and changing the given code)? Eg.

x.yo=“Hello World”
x.yo!
Hello World

T.

class << x; Y.instance_methods.each {|m| define_method m, Y.method(:m)};
end

kind of. brings in Object onwards, though, but that’s easy to fix.

-ehird

3

On Mar 1, 4:40 pm, “Elliott H.” [email protected]
wrote:

class Y
Hello World

T.

class << x; Y.instance_methods.each {|m| define_method m, Y.method(:m)}; end

kind of. brings in Object onwards, though, but that’s easy to fix.

Almost but not quite. You’d have to use Y.instance_method(:m) instead,
but then you get an error anyway because Y is not a subclass of X or
something to that effect.

I don’t think there is any reasonable way. It’s too bad. After the
discussion on MP, I decided to take a second shot at better
encapsulation of Facets. One idea was to just have a special way to
load them --if I could do the above that would work. But no go there
and nfortunately the traditional module namespaces doesn’t work well
either --they can’t handle aliasing of built-in methods and the double
module inclusion problem means it won’t work for modules either.

Ruby really needs some fixing in this area!

To clarify the problem a faux example:

module Facets
module Comparable
alias_method :gte, :>= # no method to alias
def ccc; “ccc”; end
end
end

module Comparable
include Facets::Comparable
end

10.ccc #=> NoMethodError

T.