On 8/2/07, Neil Cerutti <[EMAIL PROTECTED]> wrote: > On 2007-08-02, [EMAIL PROTECTED] <[EMAIL PROTECTED]> wrote: > > I don't personally use __call__ methods in my classes, but I > > have encountered it every now and then here at work in code > > written by other people. The other day I replaced __call__ > > with a more obvious method name, so now instead of executing > > > > obj(foo, bar, baz) > > > > the code in question is > > > > obj.execute(foo, bar, baz) > > > > In this case there was a bug. Depending on inputs, sometimes > > obj initialized to a class, sometimes an instance of that > > class. (I fixed that too while I was at it.) The problem was > > that the use of __call__ obscured the underlying bug by making > > the instance as well as the class callable. > > > > In this particular case it was clearly unnecessary and just > > obfuscated the code. I'm wondering, are there some general > > cases where __call__ methods of a user-defined class are simply > > indispensable? > > In C++ they are called functors, and they are very useful as > surrogate functions with state. I haven't seen them used in the > same way in Python much, because Python has more immediate > solutions to (most of) these problems. >
I don't think I've ever written one (in Python) except to demonstrate how it worked. Pythons built in functions have all the functionality that you'd have to use a functor for in C++. -- http://mail.python.org/mailman/listinfo/python-list
