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isFloat: Without Exception-Handling

James T. Dennis jadestar at idiom.com
Fri Oct 4 20:38:08 EDT 2002 
Mark McEahern <marklists at mceahern.com> wrote:
> [Thomas Guettler]
>> Is there a way to write the following method without using exceptions?

> Please help me understand your aversion to the original code you posted.
> IMHO, it has several salient characteristics:

> 1.  It works.
> 2.  It works.
> 3.  It works.

> Did I forget to mention:

> It works.

> Anyway, I'd modify your original function slightly to use True/False
> (builtin as of 2.2.1) and to be explicit about which errors we're ignoring:

> def isFloat(s):
>     is_float = True
>     try:
>         float(s)
>     except (ValueError, TypeError), e:
>         is_float = False
>     return is_float

 What's wrong with:

 def isFloat(s):
	try: return float(s) and True
	except (ValueError, TypeError), e: return False 

 It seems more concise and clear to skip the temp variable and 
 assignments.

 (The 'and True' part of the first return expression implicitly coerces 
 the return result to be a boolean, while the phrase: "and True" seems 
 clear enough in English, a little stilted, but still good enough English).
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