On Mon, Nov 29, 2010 at 1:21 AM, Michael Foord <fuzzyman@voidspace.org.uk> wrote:

On 28 November 2010 22:37, cool-RR <cool-rr@cool-rr.com> wrote:
`issubclass(1, list)` raises an Exception, complaining that `1` is not a class. This is wrong in my opinion. It should just return False.

Use case: I have an object which can be either a list, or a string, or a callable, or a type. And I want to check whether it's a sub-class of some base class.

So I don't think I should be taking extra precautions before using `issubclass`: If my object is not a subclass of the given base class, I should just get `False`.

Unfortunately it would be a backwards incompatible change. Currently catching the TypeError from issubclass is a way of detecting that an object *isn't* a type.

Who is doing that?! What's wrong with something like `isinstance(thing, (type, types.ClassType))`?