[Python-Dev] cpython: Rename contextlib.ignored() to contextlib.ignore(). (original) (raw)

Antoine Pitrou solipsis at pitrou.net
Wed Oct 16 13:50:46 CEST 2013

Le Wed, 16 Oct 2013 13:42:34 +0200, Victor Stinner <victor.stinner at gmail.com> a écrit :

I might agree with idea of contextlib.ignore() (I'm still opposed to the idea), but I don't understand the purpose of adding a new syntax doing exactly the same than try/except:

> with trap(OSError) as cm: > os.unlink('missing.txt') > if cm.exc: > dosomething() Nobody noticed that this can be written: try: os.unlink('missing.txt') except OSError as err: # do something with err ?? What happened with the Zen Principle "There should be one-- and preferably only one --obvious way to do it." I don't understand why I would import contextlib and use a new context manager, whereas try/except is already a builtin feature of Python. By the way, what are the performances of contextlib.ignore()? Exceptions can be slow in some cases. Adding something even slower would not be a good idea.

A "try" block which succeeds is fast. A context manager will always be slower, especially when written in pure Python with a generator wrapped in a contextlib.contextmanager.

Regards

Antoine.

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