On Jul 8, 2005, at 4:46 PM, Brett Cannon wrote:
> I think having basic context managers in a stdlib module that we know
> for a fact that will be handy is a good idea. We should keep the list
> short and poignant, but we should have something for people to work
> off of. The ones I like below for a 'context' module are:
>
>> * builtins: with open/file
>> * sys: with sys.redirected_std[in|out|err]
>> * decimal: with decimal.Context
>> * os: with os.current_directory
>> * mutex: with mutexobj
>> * threading: with threading.Lock
>> with threading.Condition
>> with threading.Event
>> * bz2/zipfile/tarfile: with ...open
It is a really bad idea to codify the practice of modifying non-
threadlocal global state like sys.std[in|out|err] and current
directory with a context manager. A user can do it to themselves now,
true, but by putting a context manager for it in the stdlib, you make
it look like it'd be a local modification when it is not. I can only
see confusion resulting from this. Users will inevitably try to use
it like
with sys.redirected_stderr(f):
print "hello"
print "there"
instead of explicitly writing to f with print>> or write(). And that
is just a terribly bad idea. It looks pretty, yes, but unless
stdinouterr are made thread-local, it's just asking for trouble.
James
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