On Mon, 11 Feb 2008 10:37:18 -0500, Neal Becker <[EMAIL PROTECTED]> wrote:
>This will work for stdout:
>
>from __future__ import with_statement
>from contextlib import contextmanager
>import sys
>
>@contextmanager
>def redirect(newfile):
> orig_stdout = sys.stdout
> sys.stdout = newfile
> yield
> sys.stdout = orig_stdout
>
>if __name__ == "__main__":
> with redirect (open('stdout', 'w')):
> print "hello"
>
> print "we're back"
>
>But now, a harder puzzle that I'm stumped on. Rewrite the above so that it
>doesn't hardcode sys.stdout, ie:
>
>def redirect (newfile, oldfile=None)
>
>where default oldfile is sys.stdout. This seems much trickier.
You just have to parameterize oldfile. The simplest way is with an object
and an attribute name.
@contextmanager
def redirect(fileholder, filename, newfile):
orig = getattr(fileholder, filename)
setattr(fileholder, filename, newfile)
yield
setattr(fileholder, filename, orig)
with redirect(sys, 'stdout', open('stdout', 'w')):
...
Note that this really has nothing to do with redirection specifically,
anymore. It's a general monkey-patching context manager.
Jean-Paul
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