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Exception handling wart in Python

Andreas Kostyrka andreas at mtg.co.at
Sun Nov 4 06:29:29 EST 2001 
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Am Samstag, 3. November 2001 00:08 schrieben Sie:
> To actually *wait* for most common exceptions to happen is definitely one
> strategy.  But somehow I don't feel that this is a "scientific" (for the
> lack of the better word) way of doing it.
>
> Regarding the binding problem with:
>
> a, b = c(d)
>
> This really goes to the issue of generic programming.  It seems like every
> function in Python is generic, but in reality it is not so.  In the real
But Python treats all names only as references to objects. Sometimes this 
happen to be function objects. So while you are quite right in assuming that 
there are some functions that make only sense with certain parameter types, 
this doesn't help anyway, because any name might be rebound.

So on the surface, a=int(b) make only sense for type(b)==types.StringType and 
a should be afterwards type(a)==types.IntegerType.

But infact int might be bound to completly something else. One case that 
happens quite often in my code is local variables and parameters named "str".

> world (in Python) there is a class of functions that can be and truly are
> generic, and there is a much bigger class of functions (in Python) that
> really only make sense with particular data types.  Perhaps, it would be a
> good idea to give the exception flow checker tool some hints in the source
> code about the function being generic or not.  That way you can avoid the
> problem of seemingly being asked to handle *all* possible exceptions in
> generic functions.  Or, perhaps, it might be a good idea to assume that
> all generic functions do not belong inside class objects.  Perhaps only
> class object methods should be checked for exception handling?
Class object methods are just function objects as any other. ;)

Andreas
- -- 
Andreas Kostyrka; Raiffeisenstr. 16/9; 2320 Zwölfaxing
Tel: +43/676/4091256; Fax: +43/1/7065299
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