[Python-Dev] file()

Georg Brandl g.brandl at gmx.net
Mon Jun 12 21:35:59 CEST 2006

Guido van Rossum wrote:
> On 6/12/06, Georg Brandl <g.brandl at gmx.net> wrote:
>> Guido van Rossum wrote:
>> > Yup, although it's a change in behavior that would need to be studied
>> > carefully for backwards incompatibilities. Usually it's given as a
>> > constant, so there won't be any problems; but there might be code that
>> > receives a mode string and attempts to test its validity by trying it
>> > and catching IOError, such code would have to be changed.
>> >
>> > --Guido
>> >
>> > On 6/12/06, Kristján V. Jónsson <kristjan at ccpgames.com> wrote:
>> >> I notice that file() throws an IOError when it detects an invalid mode
>> >> string.  Wouldn't a ValueError be more appropriate?
>> >
>> The situation is even more complex with the current trunk. open() raises
>> ValueError if it detects an invalid the mode string, such as universal
>> newline mode and a writable mode combined (the definition of
>> what is invalid has been made stricter, the mode string now must begin
>> with r, w, a or U), but it raises IOError if the OS call to fopen() fails
>> because of an invalid mode string. This might need unification.
> That would be hard to fix unless we get rid of the stdio-based
> implementation (which I intend to do in Py3k). I say we leave it alone
> for now -- fopen() can fail for any number of platform-dependent
> reasons and we can't really expect to do look-before-you-leap on this.

One option would be to raise IOError in the former case too. That's what
I meant with "unification".


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