try -> except -> else -> except?

[Python]

On 6 jul 2009, at 17:46, David House wrote:

> Hi all,
>
> I'm looking for some structure advice. I'm writing something that
> currently looks like the following:
>
> try:
>    <short amount of code that may raise a KeyError>
> except KeyError:
>    <error handler>
> else:
>    <nontrivial amount of code>
>
> This is working fine. However, I now want to add a call to a function
> in the `else' part that may raise an exception, say a ValueError. So I
> was hoping to do something like the following:
>
> try:
>    <short amount of code that may raise a KeyError>
> except KeyError:
>    <error handler>
> else:
>    <nontrivial amount of code>
> except ValueError:
>    <error handler>
>
> However, this isn't allowed in Python.
>
> An obvious way round this is to move the `else' clause into the  
> `try', i.e.,
>
> try:
>    <short amount of code that may raise a KeyError>
>    <nontrivial amount of code>
> except KeyError:
>    <error handler>
> except ValueError:
>    <error handler>
>
> However, I am loath to do this, for two reasons:
>
> (i) if I modify the <nontrivial amount of code> block at some point in
> the future so that it may raise a KeyError, I have to somehow tell
> this exception from the one that may be generated from the <short
> amount of code that may raise a KeyError> line.
> (ii) it moves the error handler for the <short amount of code that may
> raise a KeyError> bit miles away from the line that might generate the
> error, making it unclear which code the KeyError error handler is an
> error handler for.
>
> What would be the best way to structure this?
>
> -- 
> -David
>

as far as I know try has no 'else'
it's 'finally'

try:
	a
except:
	b
except:
	c
finally:
	d

gr
Arno