inline exception handling in python

Thomas Jollans thomas at
Thu Aug 12 20:08:01 CEST 2010

On Thursday 12 August 2010, it occurred to wheres pythonmonks to exclaim:
> try:
>    f = n / d
> except:
>    f = float("nan")

A catch-all except clause. Never a good idea. It's not as bad in this case, as 
there is only one expression, but there are still a couple of other exceptions 
that have a chance of occurring here: KeyboardInterrupt and SystemExit.

    f = n / d
except ZeroDivisionError:
    f = float('nan')

> f = n / d except float("nan");

So this syntax really isn't adequate for real use: catch-all except clauses 
are frowned upon, and rightfully so. 

Besides, more often than not, you want to have a finally clause around when 
you're dealing with exceptions.

> (Obviously, I am thinking about more complicated functions than "n/d"
> -- but this works as an example.)

The more complex the function is, the more likely it is to raise an exception 
you can't handle that easily.

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