How does compare work?

[Josiah Carlson]

> But silently(!) comparing apples with pears is evil. E.g. the example I 
> came across this was
> 
> thresh=raw_input('enter threshold')
> ...
> level=2
> ...
> if level > thresh :
> 
> which failed miserably. By the way, Perl does convert the string to an 
> integer silenty and, as most of the time, these Perl conversions are 
> just what one wants, so here.
> Nevertheless, I'd prefer an exception in this case since automatic 
> conversions can never be right in all circumstances.
> So this is a case where Python is a very dangerous language!

The comparison doesn't fail, it succeeds, just not the way you like.  If 
you want thresh to be an integer, perhaps you should say
thresh = int(raw_input('enter threshold'))

Perhaps one way to alleviate the problem is to have a special kind of 
input function:

def special_input(prompt, typ):
     a = None
     while a is None:
         if typ is int:
             r = '-?[0-9]+'
         #special cases for each kind of input
         a = re.search(r, raw_input(prompt))
         if a is not None:
             return typ(a.group(0))

Maybe a more fully featured set of input functions would be useful to 
include in the standard library.  Perhaps someone should write an 
example module and submit it.

  - Josiah