catching exceptions from an except: block

[Diez B. Roggisch]

Arnaud Delobelle schrieb:
> On Mar 7, 8:52 pm, Larry Bates <lba... at websafe.com> wrote:
> [snip]
>> Without knowing more about the functions and the variable it is somewhat
>> hard to tell what you are trying to accomplish.  If a, b, c are functions
>> that act on x when it is a different type, change to one function that
>> can handle all types.
> 
> I'm not really thinking about this situation so let me clarify. Here
> is a simple concrete example, taking the following for the functions
> a,b,c I mention in my original post.
>   - a=int
>   - b=float
>   - c=complex
>   - x is a string
> This means I want to convert x to an int if possible, otherwise a
> float, otherwise a complex, otherwise raise CantDoIt.
> 
> I can do:
> 
> for f in int, float, complex:
>     try:
>         return f(x)
>     except ValueError:
>         continue
> raise CantDoIt
> 
> But if the three things I want to do are not callable objects but
> chunks of code this method is awkward because you have to create
> functions simply in order to be able to loop over them (this is whay I
> was talking about 'abusing loop constructs').  

In your case, I don't consider it an abuse - au contraire. Because in 
such a situation where a possibly growing number of functions dealing 
with one value until one of them "fits" a loop is the natural thing to 
do, as it won't change in appearance just because you add a new 
conversion-function to some (semi-)global list. I'd consider it 
especially good style in that case.

Diez