En Sun, 06 Sep 2009 21:20:52 -0300, Stephen Hansen <apt.shan...@gmail.com>
escribió:
On Sun, Sep 6, 2009 at 4:31 PM, r <rt8...@gmail.com> wrote:
On Sep 6, 1:14 pm, "Jan Kaliszewski" <z...@chopin.edu.pl> wrote:
> 05-09-2009 r <rt8...@gmail.com> wrote:
> > i find the with statement (while quite useful in general
> > practice) is not a "cure all" for situations that need and exception
> > caught.
But what does that even mean? What's the -problem- that it isn't
'curing'?
That 'with' doesn't completely replace all uses of 'try'? It was never
meant
to-- that seems like a completely different problem area. But, if you do
want it to handle exception catching, that's just a question of making a
context manager that does so.
import contextlib
@contextlib.contextmanager
def file_with_errorhandling(filename, mode,
exceptions=(IOError,OSError)):
fp = file(filename, mode)
try:
yield fp
except exceptions:
print "Handle file-operation errors gracefully here."
fp.close()
with file_with_errorhandling(filename, 'r') as fp:
fp.read() # or whatever
True, the context manager provided by file objects just lets exceptions
propagate up but that's usually the desired behavior. You can make
context
managers for particular problems you run across that handle exceptions if
you want.
Note that to correctly emulate the file built-in context manager,
fp.close() should be inside a finally clause.
The with statement isn't about never having to type try again, I don't
think.
The with statement is intended as a replacement for common try/finally
blocks, not try/except blocks as the OP seems to imply.
--
Gabriel Genellina
--
http://mail.python.org/mailman/listinfo/python-list
