[Tutor] Program review

[Kent Johnson]

Ricardo Aráoz wrote:
> looking at the simpler use, if you would have exception handling in :
> 
> try :
>     with open('/etc/passwd', 'r') as f:
>         for line in f:
>             print line
>             ... more processing code ...
> except ExceptionsOnOpening :
>     ... exception handling
> except :
>     ... exceptions inside the for
> 
> 
> 
> Whereas traditionally :
> 
> try :
>     f = open('/etc/passwd', 'r')
>     for line in f:
>         print line
>         ... more processing code ...
> except ExceptionsOnOpening :
>     ... exception handling
> except :
>     ... exceptions inside the for
> 
> 
> I don't see much difference except in the with example you have one more
> level of indentation.

The with version will close the file when the with block exits.

> Don't know about more advanced uses, I'll try to understand them when
> and if I ever need them.

Maybe 'with open(...) as ...' is more useful in contexts where you are 
not so picky about exception handling.

Here is a context manager and associated decorator you might be 
interested in - it traps errors and logs them :-)
http://blogmaker.googlecode.com/svn/trunk/blogmaker/util/trap_errors.py

Kent