[Python-Dev] [PEP 3148] futures - execute computations asynchronously (original) (raw)

Greg Ewing greg.ewing at canterbury.ac.nz
Sun Mar 7 00:19:42 CET 2010

Jeffrey Yasskin wrote:

The caller can't avoid the error here by querying the future, because of the problem you point out below, so I'm inclined to think that "the future was already started" should be a return value rather than an exception (although that may be my C++ background showing through).

I think it's your C++ background showing. In Python philosophy, there's no particlular connection between whether something can be tested for and whether it should raise an exception.

The thing to consider, I think, is whether it makes sense in a large proportion of use cases to ignore the fact that the cancel failed and carry on regardless. If not, then raising an exception makes it much harder to accidentally ignore the situation.

-- Greg

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