anonymous classes

[Ian Macdonald]

Hi,

Could someone please explain to me the concept of an anonymous class?

I'm talking about this construct:

class << Foo
...
end

I'm having a hard time understanding the books and figuring out when I
might actually want/need to use this.

Ian
--
Ian Macdonald | Keep cool, but don't freeze. -- Hellman's
System Administrator | Mayonnaise
(e-mail address removed) |
http://www.caliban.org |
|

 

[Chad Fowler]

Hi,

Could someone please explain to me the concept of an anonymous class?

I'm talking about this construct:

class << Foo
...
end

I'm having a hard time understanding the books and figuring out when I
might actually want/need to use this.

Ian

This may be a good starting point:

http://www.rubygarden.org/ruby?ClassMethods

Chad

 

[Ian Macdonald]

What you've written is called a "singleton class". I wrote this a while:

http://www.rubygarden.org/ruby?SingletonTutorial

It might be helpful and includes a couple of links to more detailled
information.

Thanks. This is an excellent resource and makes things a lot clearer.

Ian
--
Ian Macdonald | Yes, we will be going to OSI, Mars, and
System Administrator | Pluto, but not necessarily in that order.
(e-mail address removed) | -- Jeffrey Honig
http://www.caliban.org |
|

 

[Dominik Werder]

What you've written is called a "singleton class". I wrote this a while:

http://www.rubygarden.org/ruby?SingletonTutorial

it is very helpful for me too

One question referring to
"A neat solution then is to create a singleton class for each POP3
connection as it arrives: "
How much memory does this technique consume? Are the new methods created
for each individual instance? Or just something like a lookup table?

bye!
Dominik

 

[Brian Candler]

it is very helpful for me too

One question referring to
"A neat solution then is to create a singleton class for each POP3
connection as it arrives: "
How much memory does this technique consume? Are the new methods created
for each individual instance? Or just something like a lookup table?

All that happens is that a new proxy class is added to the object, which
points at the module which you #extended it with. It certainly doesn't copy
all the methods.

You can prove this easily enough, by modifying the module *after* you have
done extend:

module A
end
a = "hello"
a.extend A
b = "world"
b.extend A

module A
def foo
puts "it works"
end
end
a.foo #=> "it works"
b.foo #=> "it works"

You can see that the two objects share the same module implementation.

Regards,

Brian.