[Python-Dev] file()

Guido van Rossum guido at python.org
Mon Jun 12 21:34:44 CEST 2006

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.

--Guido van Rossum (home page: http://www.python.org/~guido/)

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