On Sun, 30 May 2010 05:49:45 am Alex Hall wrote:
> Hi all,
> In Battleship, I have a weapons.py file, currently with just one
> missile type (a Harpoon anti-ship missile). This Harpoon class
> defines a getImpactCoords method, which returns all coordinates on
> the map that it will hit. I would like to not instantiate a Harpoon
> object, just call the Harpoon's getImpactCoords method and pass it
> the required arguments.
I don't understand the logic here. Surely the impact coordinates depends
on the individual missile (an instance)?
> Is this possible? Thanks. Sorry if I got the
> terms backwards in the subject; I can never remember which is static
> and which is non-static.
In Python terminology, a static method is an ordinary function that is
called as a method from either a class or a class instance:
class C(object):
@staticmethod
def method(x):
return "Called with argument %s", % x
Note that the method does not receive an automatic instance argument
(usually called self) when you call it.
A class method is like an ordinary method, except instead of receiving
the instance (self) as the first argument, it receives the class
(usually called cls):
class C(object):
@classmethod
def method(cls, x):
return "Called from class %s with argument %s", % (cls, x)
The method always receives the class, regardless of whether you call it
from the class using C.method(x) or from an instance C().method(x).
You might also be interested in what I call "dualmethod", which passes
the class as first argument if you call it from the class, and the
instance if you call it from the instance:
http://code.activestate.com/recipes/577030-dualmethod-descriptor/
--
Steven D'Aprano
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