On Fri 17 Oct 2008 04:52:47 PM EDT, Steve Holden wrote: > Matthew Wilson wrote: >> I started with a module with a bunch of classes that represent database >> tables. A lot of these classes have methods that use other classes >> inside, sort of like this: >> >> class C(object): >> @classmethod >> def c1(cls, a): >> return a >> >> class D(object): >> def d1(self, a): >> return a + C.c1(a) >> >> Notice how the d1 method on class D uses a classmethod c1 on C. C is in >> the same module, so it's globally available. >> >> I moved my classes C and D into different files, and then I noticed that >> D now needed to import C first. That worked fine until I wrote >> interdependent classes that couldn't import each other. >> >> So I passed in everything as parameters like this: >> >> def d1(self, C, a): >> >> That works fine, but now I've got some methods that have six >> parameters (or more) that are entirely just for this purpose. So, now >> instead of passing these in as parameters, I'm passing them into my >> initializer and binding them in to self. >> >> I wanted to use functools.partial to bind on these parameters like this: >> >> d1 = functools.partial(d1, C=C) >> >> But partial objects don't get the self parameter passed in, so using >> partial is is effectively similar to decorating methods with >> staticmethod. Here's a link to the documentation on partial that >> explains this: >> >> http://www.python.org/doc/2.5.2/lib/partial-objects.html >> >> So, partials won't work. >> >> I suspect that there's more elegant solutions for this. >> >> All thoughts are welcome. > > Explain why you are using classmethods instead of regular methods in the > first case (I appreciate your actual code will be rather more complex > than your examples).
Hi Steve, I'm using SQLObject classes, and joining one table with another requires either the class or an instance for the class. So, I could pass in instances of all the classes, and I'd be at the same point. I just don't like seeing functions with lots and lots of parameters. Thanks for the feedback! -- http://mail.python.org/mailman/listinfo/python-list
