How to determine what exceptions a method might raise?

George Sakkis george.sakkis at
Wed Jan 17 09:34:54 CET 2007

Ben Finney wrote:

> Ed Jensen <ejensen at> writes:
> > it would be handy if there was something I could do in the
> > interactive interpreter to make it tell me what exceptions the file
> > method might raise (such as IOError).
> For what purpose would this be handy? Surely the benefit of the
> interactive interpreter is that you can simply try it out and *see*
> what happens.
> But, in case it helps: Any code may raise any exception at any
> time. This is a feature, since it encourages program that are tested
> properly.

That's a silly argument, really, unless perhaps you'd consider a box of
pills that look like M&Ms a 'feature' since it encourages parents to
hide them from their kids. A better answer would be along the lines of
"yes, that would be nice to have but in general it's not possible in a
dynamic language; that's the price you have to pay for leaving the
static typing world".

As for the OP's question, since file is a fixed builtin, I think it
should be possible to know all the possible exceptions that can be
raised; I'm not sure if it's clearly documented though.


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