If you find yourself writing a class and you can’t explain the difference between the class and an instance of that class, just stop. You should be writing a function.
This antipattern — needless classes everywhere, for everything — is driving me crazy. Lately I see it in Python and Ruby a good bit, where it really shouldn’t occur. I feel like its a mental contagion that has jumped species from Java to other languages.
In particular I see classes used as inter-module namespaces, which is odd since its not like there is a tendency to run out of meaningful names within a single source file (of reasonable length). Importing the module from outside can either import * from foo,or import foo, or from foo import filename, or even import foo as bar (ah ha!) and make flexible use of namespacing where it is needed most — in the immediate vicinity of use.
So don’t write useless, meaningless, fluffy, non-state&behavior classes. Any time you can avoid writing classes, just don’t do it. Write a function. Its good discipline to see how far you can get writing zero classes in an implementation, and then write it with some classes and see which is actually less complex/more readable. In any case writing two solutions will give you a chance to examine the problem from multiple angles, and that’s nearly always an effort that results in better code since it forces you to value grokness over hacking together a few lines that sort of cover the need for the moment (and forgetting to ever come back and do it right).
Or maybe I should be admonishing people to seek flatness in namespaces, since this implies not writing classes that are stateless containers of a bunch of function definitions which incidentally get referred to as “methods” even though they don’t belong to a meaningful object in the first place.
Or maybe I should be railing against the oxymoronic concept of “stateless objects/classes”.
Or maybe I should be screaming about keeping our programming vocabulary straight so that we can finally say what we mean and mean what we say. (Sound advice in all walks of life.)
This last idea is perhaps the most indirect yet powerful of all. But it implies “standards” and so far in my experience “standards” and “computing” don’t tend to turn out very well once we get beyond, say, TCP/IP or ANSI and Unicode.