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[Python-Dev] When to use EOFError?

Random832 random832 at fastmail.com
Mon Jun 27 20:31:35 EDT 2016 
On Mon, Jun 27, 2016, at 12:40, Ethan Furman wrote:
> On 06/21/2016 01:48 PM, Serhiy Storchaka wrote:
> 
> > There is a design question. If you read file in some format or with some
> > protocol, and the data is ended unexpectedly, when to use general
> > EOFError exception and when to use format/protocol specific exception?
> 
> I believe that EOFError was created for the situation when a file 
> unexpectedly ends.

The problem is that's not a good abstraction for the class of errors
we're discussing, because it means you've got to pick: the thing your
parser parses is a file [and non-files are supported by wrapping them in
a StringIO/BytesIO] or it is a str/bytes [and files are supported by
reading their data into a string].

Or you could use a third option: a method that accepts a file raises
EOFError, and a method that accepts a string raises some other error
(ValueError?), and if either is implemented in terms of the other it's
got to wrap the exception.

(Also, that's nonsense. EOFError is also used when a file *expectedly*
ends - EAFP i.e. "Exceptions As Flow-control is Pythonic" ;)
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