On 15 avr, 17:43, Robert Bossy <[EMAIL PROTECTED]> wrote: > Reckoner wrote: > > would it be possible to use one of an object's methods without > > initializing the object? > > > In other words, if I have: > > > class Test: > > def __init__(self): > > print 'init' > > def foo(self): > > print 'foo' > > > and I want to use the foo function without hitting the > > initialize constructor function. > > > Is this possible? > > Hi, > > Yes. It is possible and it is called "class method". That is to say, it > is a method bound to the class, and not to the class instances. > In pragmatic terms, class methods have three differences from instance > methods: > 1) You have to declare a classmethod as a classmethod with the > classmethod() function, or the @classmethod decorator. > 2) The first argument is not the instance but the class: to mark this > clearly, it is usually named cls, instead of self. > 3) Classmethods are called with class objects, which looks like this: > ClassName.class_method_name(...). > > In your example, this becomes: > > class Test(object): > def __init__(self): > print 'init' > @classmethod > def foo(cls): > print 'foo' > > Now call foo without instantiating a Test: > Test.foo()
To be complete, you can also define a static method that will not even be passed the class as argument: In [217]: class Test(object): .....: def __init__(self): .....: print 'init' .....: @staticmethod .....: def foo(): .....: print 'foo' .....: In [218]: Test.foo() foo -- http://mail.python.org/mailman/listinfo/python-list
