Why not 3.__class__ ?

[Martin von Loewis]

James_Althoff at i2.com writes:

> Given that, it's nice to use the same idiom when y is a builtin type, as in
> isinstance(x,''.__class__)
> isinstance(x,0 .__class__)
> isinstance(x,[].__class__)
> isinstance(x,().__class__)
> isinstance(x,{}.__class__)
> 
> instead of using a second idiom for builtins
> 
> import types
> isinstance(x,types.IntType)

So what's wrong with

isinstance(x,str)
isinstance(x,int)
isinstance(x,list)
isinstance(x,tuple)
isinstance(x,dictionary)

> At a higher level it seems that if you want to do an "isinstance" test, it
> is nicer to use the class object that you already have "in hand" (or can
> easily get to with a literal constant) rather than having to know about an
> external module

For the builtin types (in particular those that have literals), you do
have the class object "in hand", no need to obtain it from an instance.

Regards,
Martin