On Tue, Mar 31, 2020 at 2:41 AM Serhiy Storchaka <storch...@gmail.com>
wrote:
> 31.03.20 01:32, Christopher Barker пише:
> > In case Serhiy's answer wasn't clear: context managers can be written to
> > handle exceptions (within their context) in any way you see fit.
> >
> > that is: the method:
> > |
> > |
> > |__exit__(||self||, exc_type, exc_value, exc_traceback):|
> >
> > get the exception, and information about it, of one is raised, so you
> > can handle it anyway you want.
>
> Actually I meant the opposite.
I think I was thrown by the use of the example "my_context" -- that is, if
you are writing a conrtect manger, you can handle exceptions any way you
like. If you are using an existing one, then, yes:
> the context manager does not silence a raised exception, so control flow
> is never passed to the statement past the with block if an exception is
> raised inside the with block.
>
> was_not_raised = False
> with my_context():
> do_something_sensitive()
> was_not_raised = True
> if was_not_raised:
> print("We're all safe.")
>
> You do not need a special syntax for this.
but we don't need special syntax for "else" on a for or while loop (or try
block) either, you could always set a sentinel for those too.
which to me is a case for adding else to a "with" block as well, for all
the same reasons it's there for the other block construct.
Though I don't think I'd advocate it in this case, as the Exception is not
really a clear part of the context manger API, like "break" is to the loops.
-CHB
--
Christopher Barker, PhD
Python Language Consulting
- Teaching
- Scientific Software Development
- Desktop GUI and Web Development
- wxPython, numpy, scipy, Cython
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