[Python-Dev] file() (original) (raw)

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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