Why would I use inspect.isclass()?

[Steve Holden]

Martin v. Löwis wrote:

> it's me wrote:
> 
>> Okay, Nick, I didn't know you can pass a "Class" rather then an 
>> instance.  I
>> have to chew on what your example does.
>>
>> But no, I want to pass an instance of a Class.  But how do I know that 
>> the
>> calling routine *did* pass me a class - pardon me: an instance of a 
>> Class?
> 
[...]
> 
> The real purpose of why you have *inspect*.isclass is for inspecting.
> For example, assume I wanted to display the contents of module httplib.
> I would need to find out what the things in httplib are, and I do this
> with
> 
>  >>> for x in dir(httplib):
> ....   print x,
> ....   x = getattr(httplib, x)
> ....   if inspect.isclass(x):print "class"
> ....   elif inspect.isfunction(x):print "function"
> ....   elif inspect.ismodule(x):print "module"
> ....   else: print "something else"
> ....

This technique is often called "introspection", and involves having 
programs indulge in the time-honored practice of contemplating their own 
navels. The ability to introspect is one side of a major dichotomy in 
programming languages. A C program has no real ability to introspect, 
but Python and SmallTalk (and Java) programs do.

But it isn't really a novice topic, and many programmers spend entire 
careers quite happily without using introspection.

regards
  Steve
-- 
Steve Holden               http://www.holdenweb.com/
Python Web Programming  http://pydish.holdenweb.com/
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