[Python-3000] StringIO/BytesIO in io.py doesn't over-seek properly

[Alexandre Vassalotti]

On 6/23/07, Guido van Rossum <guido at python.org> wrote:
> On 6/23/07, Alexandre Vassalotti <alexandre at peadrop.com> wrote:
> > I think found a bug in the implementation of StringIO/BytesIO in the
> > new io module.  I would like to fix it, but I am not sure what should
> > be the correct behavior. Any hint on this?
>
> BytesIO should behave the way Unix files work: just seeking only sets
> the read/write position, but writing inserts null bytes between the
> existing end of the file and the new write position. (Writing zero
> bytes doesn't count; I've just experimentally verified this.)

I agree with this. I will try to write a patch to fix io.BytesIO.

> I think however that for StringIO this should not be allowed -- seek()
> on StringIO is only allowed to accept cookies returned by tell() on
> the same file object.

I am not sure what you mean, by "cookies", here. So, do you mean
StringIO would not be allowed to seek beyond the end-of-file?

> > And one more thing, the close method on StringIO/BytesIO objects
> > doesn't work.  I will try to fix that too.
>
> What do you want it to do? I'm thinking perhaps it doesn't need to do anything.

Free the resources held by the object, and make all methods of the
object raise a ValueError if they are used.

-- Alexandre