On Saturday, October 5, 2013 9:04:25 PM UTC-7, John Ladasky wrote: > Hi folks, > > > > I'm trying to make some of Python class definitions behave like the ones I > find in professional packages, such as Matplotlib. A Matplotlib class can > often have a very large number of arguments -- some of which may be optional, > some of which will assume default values if the user does not override them, > etc. > > > > I have working code which does this kind of thing. I define required > arguments and their default values as a class attribute, in an OrderedDict, > so that I can match up defaults, in order, with *args. I'm using > set.issuperset() to see if an argument passed in **kwargs conflicts with one > which was passed in *args. I use set.isdisjoint() to look for arguments in > **kwargs which are not expected by the class definition, raising an error if > such arguments are found. > > > > Even though my code works, I'm finding it to be a bit clunky. And now, I'm > writing a new class which has subclasses, and so actually keeps the "extra" > kwargs instead of raising an error... This is causing me to re-evaluate my > original code. > > > > It also leads me to ask: is there a CLEAN and BROADLY-APPLICABLE way for > handling the *args/**kwargs/default values shuffle that I can study? Or is > this sort of thing too idiosyncratic for there to be a general method? > > > > Thanks for any pointers!
"One thought -- often, people turn to subclassing as the only tool in their toolbox. Have you considered that it may be easier/better to work with delegation and composition instead? " Double like. Subclassing is awesome when it is used properly ... which usually means used cautiously. Delegation/composition just doesn't result in the some sort of weird gotchas. -- https://mail.python.org/mailman/listinfo/python-list
