True inconsistency in Python

[Tim Roberts]

Scott Chapman <scott_list at mischko.com> wrote:
>
>Historically Python has allowed <> 0 to equal true in evaluations.  Now 
><> 0 still evaluates to true in evaluations. However it doesn't equal  
>True.  They are not interchangable.  (Same with empty lists, etc.) 

Python is certainly not the only language in which this occurs.  Many are
the C programmers who have been burned by:

  int SomeFunction();
    ...
  if( SomeFunction == TRUE )
  {
  }

Visual Basic has exactly the same problem.  Further, until very recently,
True in VB actually evaulated to -1, so even comparing to "1" would fail.

This should not be a surprise.  Booleans should be thought of as enumerated
integral types.

>Assuming the old behavior is desired, programmers need to be careful 
>not to compare a variable with True as in:
>
>if var == True: # only works if var is 1
>  blah

Your statement is absolutely true.  End of story.
-- 
- Tim Roberts, timr at probo.com
  Providenza & Boekelheide, Inc.