Hi --
On Mon, 13 Jul 2009, Buzz Hill wrote:
>
> JangoSteve wrote:
>> In other words, you just use def get_payment_types if
>> get_payment_types is to be performed on a specific instance of that
>> class, and def self.get_payment_types if it is just a generic function
>> for that class...
>
> I guess what I am confused about is this:
>
> Dave Thomas talks about self as a special variable used by Ruby to
> maintain a reference to the context of where the interpreter is
> operating and any given point, so it knows where to find a particular
> method. So why does Ruby not seem to know the context of
> "get_payment_types" without the self. Here is a slight variation on the
> previous code:
I think you're confusing defining a method with calling a method. self
always serves as the default receiver for messages -- meaning that
this:
my_method(a,b,c)
is interpreted as this:
self.my_method(a,b,c)
When you're defining a method, if you designate a specific object for
the method, like this:
def my_object.some_method(a,b,c)
# ...
end
then the method will be a singleton method on that object -- meaning
that the method is available only to that object.
So when you do this:
class Something
def self.greet
puts "Hello from #{self}!"
end
end
you're defining a method on the object self -- which happens to be, at
that point in execution, the class object Something.
There's a bit more to it, but am I on the right track, in terms of
what you're finding confusing?
David
--
David A. Black / Ruby Power and Light, LLC
Ruby/Rails consulting & training: http://www.rubypal.com
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