[Python-3000] patch: bytes object PyBUF_LOCKDATA read-only and immutable support (original) (raw)

Gregory P. Smith greg at krypto.org
Sun Sep 9 01:15:58 CEST 2007

A new version is attached; cleaned up and simplified based on your original comments.

On 8/29/07, Guido van Rossum <guido at python.org> wrote:

That's a huge patch to land so close before a release. I'm not sure I like the immutability API -- it won't be useful unless we add a hash method, and then we have all sorts of difficulties again -- the distinction between a hashable and an unhashable object should be made by type, not by value (tuples containing unhashable values notwithstanding).

ok i've removed the immutable support in the most recent patch. i still think it -might- be useful but isn't required and you're right that it could open a can of worms if people think it should also mean hashable. immutable bytes may be best implemented as a subclass if its ever wanted.

I don't understand the comment about using PyBUF_WRITABLE in

getbuffer() -- this is only used for data we're reading and I don't think the GIL is even released while we're reading such things.

that appears to be correct. the comment was wrong. fixed.

-gps

If you think it's important to get this in the 3.0a1 release, we

should pair-program on it ASAP, preferable tomorrow morning. Otherwise, let's do a review next week.

--Guido On 8/29/07, Gregory P. Smith <greg at krypto.org> wrote: > Attached is what I've come up with so far. Only a single field is > added to the PyBytesObject struct. This adds support to the bytes > object for PyBUFLOCKDATA buffer API operation. bytes objects can be > marked temporarily read-only for use while the buffer api has handed > them off to something which may run without the GIL (think IO). Any > attempt to modify them during that time will raise an exception as I > believe Martin suggested earlier. > > As an added bonus because its been discussed here, support for setting > a bytes object immutable has been added since its pretty trivial once > the read only export support was in place. Thats not required but was > trivial to include. > > I'd appreciate any feedback. > > My TODO list for this patch: > > 0. Get feedback and make adjustments as necessary. > > 1. Deciding between PyBUFSIMPLE and PyBUFWRITEABLE for the internal > uses of the getbuffer() function. bytesobject.c contains both readonly > and read-write uses of the buffers, i'll add boolean parameter for > that. > > 2. More testing: a few tests in the test suite fail after this but the > number was low and I haven't had time to look at why or what the > failures were. > > 3. Exporting methods suggested in the TODO at the top of the file. > > 4. Unit tests for all of the functionality this adds. > > NOTE: after these changes I had to make clean and rm -rf build before > things would not segfault on import. I suspect some things (modules?) > were not properly recompiled after the bytesobject.h struct change > otherwise. > > -gps > > _> ________________________ > Python-3000 mailing list > Python-3000 at python.org > http://mail.python.org/mailman/listinfo/python-3000 > Unsubscribe: http://mail.python.org/mailman/options/python-3000/guido%40python.org > > >

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