Is 'isinstance()' the right thing?

[Bill Dozier]

Erik Max Francis <max at alcyone.com> wrote in message news:<3CCE5F2A.1103E744 at alcyone.com>...

> Ralf Juengling wrote:

> 

> > when I want to make sure within a function that it can deal with

> > the arguments passed, the only choice is to check it's type via

> > 'isinstance()'.
> > So, what is the proper, 'pythonic' way of argument checking?

> 

> The "Pythonic" way of argument checking is to simply use it and catch

> the exceptions that will be thrown if it doesn't behave as planned.

> 


IMHO, "isinstance()" is usually not the right thing. Whether it's
"pythonic" or not, I can't say.

When you have code that checks the type of an object and then treats
it accordingly, it's usually a sign that you need to use some
polymorphism. Of course, you don't always have the luxury of fixing
the design.

Bill