[Python-Dev] mmapfile module

Guido van Rossum guido@python.org
Thu, 30 Mar 2000 15:25:58 -0500

> Guido van Rossum writes:
> >I don't know enough about this, but it seems that there might be two
> >steps: *creating* a mmap object is necessarily platform-specific; but
> >*using* a mmap object could be platform-neutral.
> >
> >What is the API for mmap objects?

> You create them; Unix wants a file descriptor, and Windows wants a
> filename.  Then they behave like buffer objects, like mutable strings.
> I like Fredrik's suggestion of an 'open(filename, mode, ...)' type of
> interface.  If someone can suggest a way to handle the extra flags
> such as MAP_SHARED and the Windows tag argument, I'll happily
> implement it.  Maybe just keyword arguments that differ across
> platforms?  open(filename, mode, [tag = 'foo',] [flags =
> mmapfile.MAP_SHARED]).  We could preserve the ability to mmap() only a
> file descriptor on Unix through a separate openfd() function.

Yes, keyword args seem to be the way to go.  To avoid an extra
function you could add a fileno=... kwarg, in which case the filename
is ignored or required to be "".

> I'm
> also strongly tempted to rename the module from mmapfile to just
> 'mmap'.


> I'd suggest waiting until the interface is finalized before adding the
> module to the CVS tree -- which means after 1.6a1 -- but I can add the
> module as it stands if you like.  Guido, let me know if you want me to
> do that.

Might as well check it in -- the alpha is going to be rough and I
expect another alpha to come out shortly to correct the biggest

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