On May 28, 2:59 am, Julian Leviston <[email protected]> wrote:
> Hi,
>
> > def self.included(base)
> > base.send :extend, ClassMethods
> > end
>
> > module ClassMethods
> > def my_method
> > end
> > end
>
> This is not a class method, is it? it's an instance method. a class
> method would be
>
> def self.my_method
> end
>
>
I have all of 20 hours of Ruby experience now, so I'll probably screw
up this explanation. The whole include/extend thing is still very
confusing to me, but I'm having ActiveRecord::Base call include on my
module and attaching a callback so that I can do more.
ActiveRecord::Base is an instance of the Class class, so when the
callback uses extend, it is the ActiveRecord::Base instance itself
(and ActiveRecord::Base objects) that pick up the new my_method
instance method. My understanding is that Ruby then attaches this to
a metaclass for the ActiveRecord::Base instance, making it a singleton
method. And I think that's all class methods really are; singleton
methods on the metadata class for an instance of the Class class. So
through module trickery I have created a new class method.
If I have this wrong, let me know. I don't like to write code that I
don't understand, so the sooner I wrap my head around the actual
mechanics of how this works, the better.
>
> I don't follow what you want to do here... you're calling the method
> inside the class definition. That makes no sense. What did you want to
> happen?
> In other words, you're running a method WHILE declaring the class.
>
For any language other than ruby, I would agree that this doesn't make
sence. :)
Apparently it's standard practice though for this language. You can
run methods right in the middle of your class definition. You can try
this out pretty easily in irb:
irb(main):001:0> class A
irb(main):002:1> puts "hello!"
irb(main):003:1> end
hello!
=> nil
Strange! But useful. In my case I'm actually planning to create
three class methods similar to my_method above. When run these will
generate instance methods for my models (similar to associations).
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