[Python-Dev] When to use EOFError? (original) (raw)

Steven D'Aprano steve at pearwood.info
Mon Jun 27 20:25:42 EDT 2016

On Mon, Jun 27, 2016 at 03:47:31PM -0700, Ethan Furman wrote:

On 06/27/2016 03:20 PM, Guido van Rossum wrote:

>The point is that it's not an error. In Andre Malo's use case, at >least, EOFError is used as a control flow exception, not as an error. Like StopIteration then: only an error if it escapes.

Well, not quite -- if you're expected four pickles in a file, and get EOFError after pickle #2, then it's an actual error. But that's up to the caller to decide.

EOFError just means there's nothing more to read in a situation where returning an empty (byte) string isn't an option. The meaning you give to that depends on your expectations.

I think Greg had the right idea: raise a pickle error if you hit EOF in the middle of a pickle, because that absolutely means your data is corrupt; raise EOFError when you hit EOF at the very beginning of the file, or after a complete pickle.

-- Steve

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