[Python-Dev] context manager - generator interaction? (original) (raw)

Guido van Rossum guido at python.org
Fri Apr 6 11:39:33 CEST 2007

On 4/5/07, Raymond Hettinger <python at rcn.com> wrote:

> Guido van Rossum wrote: >> Isn't this violating the rule that a try/except should only enclose >> the smallest expression where the exception is expected? > > Yeah, and I keep finding myself wanting to hyperlink to that "rule" in > the official docs, but it only seems to be written down in developer's > heads. Can we get that into the Language Ref somewhere? Maybe on the > http://docs.python.org/ref/try.html page?

I'll add a snippet to the tutorial with advice on try/except. I don't think it should go in the main documentation because it is really more of a suggestion or technique than an actual rule. Also, there are plenty of other situations where the "rule" doesn't apply.

I see a lot of code written by Googlers who are not (yet) experienced Python users. Overly wide try/except clauses are a common mistake, and it is nearly always easy to apply this rule. I would argue, as a style issue, for making this rule the norm, and require deviations to be thought through very carefully.

This rule has no place in a pure language reference manual. But it certainly deserves mention in any form of more practical documentation, be it a tutorial or a more advanced programming manual.

-- --Guido van Rossum (home page: http://www.python.org/~guido/)

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