Why would I get a TypeEror?

[Steve Holden]

It's me wrote:

> For this code snip:
> 
> a=3
> .....
> b=(1,len(a))[isinstance(a,(list,tuple,dict))]
> 
> Why would I get a TypeError from the len function?
> 
> Thanks,
> 
> 
because the interpreter evaluates the tuple (1, len(a)) before applying 
the indexing to it.

You are trying to be far too clever. The standard way to write this 
would be:

a = 3
....
b = 1
if isinstance(a,(list,tuple,dict)):
     b = len(a)

Is code length *really* so important? Think carefully ...

regards
  Steve
-- 
Steve Holden               http://www.holdenweb.com/
Python Web Programming  http://pydish.holdenweb.com/
Holden Web LLC      +1 703 861 4237  +1 800 494 3119