Michael Powe wrote:
Clash of the Titans
From "Dive into Python":
__init__ is called immediately after an instance of the class is created. It would be tempting but incorrect to call this the constructor of the class. It's tempting, because it looks like a constructor (by convention, __init__ is the first method defined for the class), acts like one (it's the first piece of code executed in a newly created instance of the class), and even sounds like one ("init" certainly suggests a constructor-ish nature). Incorrect, because the object has already been constructed by the time __init__ is called, and you already have a valid reference to the new instance of the class. But __init__ is the closest thing you're going to get to a constructor in Python, and it fills much the same role.
From Alan's book "Learning to Program":
One of the methods of this class is called __init__ and it is a special method called a constructor. The reason for the name is that it is called when a new object instance is created or constructed. Any variables assigned (and hence created in Python) inside this method will be unique to the new instance. There are a number of special methods like this in Python, nearly all distinguished by the __xxx__ naming format.
When thinking about __init__ think not "constructor" but "initializer" (that's where the name comes from after all...). By definition, an initializer initializes something already existing, already constructed.
To *construct* a new instance one implements __new__ (python >= 2.2. See the docs).
[text snipped]
Finally, in terms of "understanding python," the question I keep coming up against is: why do we have both functions and methods? What is the rationale for making join() a string method and a os.path function?
Because functions and methods are different objects for conceptually different things? The way I tend to think of it, is that methods are functions with a little bit of extra functionality (although in the current implementation of Python functions *are* methods, or more corectly, descriptors).
For the second question, os.path would be a method of what class?
Best regards, G. Rodrigues _______________________________________________ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
