Mark Sparshatt <[EMAIL PROTECTED]> writes: > >I'm not 100% certain about the details but I think this is how it works. > >In languages like C++ objects and classes are completely seperate. >classes form an inheritance heirachy and objects are instances of a >particular class. > >However in some languages (I think that Smalltalk was the first) there's >the idea that everything is an object, including classes. So while an >object is an instance of a class, that class is an instance of another >class, which is called the metaclass. I don't there's anything special >about these classes other than the fact that their instances are also >classes. > > >Thinking about it I think you may have the relationship between >ParrotObject and ParrotClass the wrong way around. Since a class is an >object but and object isn't a class it would be better for ParrotClass >to inherit from ParrotObject, rather than the other way round. > >In Ruby when you create a class Foo, the Ruby interpreter automatically >creates a class Foo' and sets the klass attribute of Foo to point to Foo'. > >This is important since class methods of Foo are actually instance >methods of Foo'. Which means that method dispatch is the same whether >you are calling an instance of class method.
So in perl5-ese when you call Foo->method you are actually calling sub Foo::method which is in some sense a "method" of the %Foo:: "stash" object. So what you suggest is as if perl5 compiled Foo->method into (\%Foo::)->method and the %Foo:: 'stash' was blessed... > >foo.method() > >looks at foo's klass attribute then checks the returned class object >(Foo) for method > >Foo.method() > >looks at Foo's klass attribute and again checks the returned class >object (Foo') for method. > >The Pickaxe book has got a better explanation of this (at >http://www.rubycentral.com/book/classes.html though without any diagrams >:( ) > >In Python when defining a class it's possible to set an attribute in the >class that points to the classes metaclass. The metaclass itself is just >a normal class that defines methods which override the normal behaviour >of the class. > >IIRC Python has got both class methods and meta class instance methods >which work almost (but not quite) in the same way as each other. > >Hopefully someone with more experience with Python will be able to >explain better. > >I'm not sure if this has cleared things up or just made them more confusing.
