type classobj not defined?

[Peter Otten]

Wesley Brooks wrote:

> Dear Users,
> 
> I'm in the process of adding assert statements to a large piece of
> code to aid with bug hunting and came across the following issue;
> 
> Using python in a terminal window you can do the following:
> 
>>type(False) == bool
> True
> 
> I would like to check that an object is a class, here's an example:
> 
>>class b:
> ....def __init__(self):
> ........self.c = 1
> ....def d(self):
> ........print self.c
> 
>>type(b)
> <type 'classobj'>
> 
> But the following fails:
> 
>>type(b) == classobj
> Traceback (most recent call last):
>   File "<stdin>", line 1, in ?
> NameError: name 'classobj' is not defined
> 
> For the time being I'll use b.__name__ == b to ensure I'm getting the
> right class. Is there a reason why the other types such as bool are
> defined but classobj isn't?

No idea. You can easily define it yourself, though:

>>> class Classic: pass
...
>>> classobj = type(Classic)
>>> isinstance(Classic, classobj)
True

Note that "newstyle" classes (those deriving from object) are of type
'type', not 'classobj':

>>> class Newstyle(object): pass
...
>>> isinstance(Newstyle, classobj)
False
>>> isinstance(Newstyle, (classobj, type))
True

The inspect module wraps the functionality in a function:

>>> import inspect
>>> inspect.isclass(Newstyle)
True
>>> inspect.isclass(Classic)
True

Peter