As the subject says, it would be nice if mmaps were
subclassable...like nearly every other Python object type.


Note that pseudo-subclasses (copying the instance
methods to a different class (not necessarily of the
same type) instance) don't work completely due to
python.org/sf/1087735 , and is probably a Python
"anti-pattern".

Josiah, care to work up a patch?

I honestly wouldn't know where to start.  I don't know what the differences are between the currently un-subclassable mmap, and something like int/list/dict.

I'm attaching a patch, which makes mmap.mmap the mmap class itself and
also makes it subclassable. It also contains changes to the documentation.
This is against revision 60148 of trunk.

Reviewed and committed in r60152.

Many thanks for handling it immediately.

sorry, I somehow managed to introduce a segfault: 

~/pydev/trunk/ cat t.py                                                
            ralf@red ok
from mmap import mmap

class anon_mmap(mmap):
    def __new__(klass, *args, **kwargs):
        res = mmap.__new__(klass, -1, *args, **kwargs)
        print "NEW:", res
        return res

anon_mmap(4096)
~/pydev/trunk/ ./python t.py                                           
            ralf@red ok
NEW: <__main__.anon_mmap object at 0x866b10>
Debug memory block at address p=0x866b10:
    18374686479671623679 bytes originally requested
    The 8 pad bytes at p-8 are not all FORBIDDENBYTE (0xfb):
        at p-8: 0xcb *** OUCH
        at p-7: 0xcb *** OUCH
        at p-6: 0xcb *** OUCH
        at p-5: 0xcb *** OUCH
        at p-4: 0xcb *** OUCH
        at p-3: 0xcb *** OUCH
        at p-2: 0xcb *** OUCH
        at p-1: 0xcb *** OUCH
    Because memory is corrupted at the start, the count of bytes requested
       may be bogus, and checking the trailing pad bytes may segfault.
    The 8 pad bytes at tail=0xff00000000866b0f are zsh: segmentation
fault  ./python t.py



The following fixes it for me:

~/pydev/trunk/ cat patch                                               
    ralf@red failed 139
diff --git a/Modules/mmapmodule.c b/Modules/mmapmodule.c
--- a/Modules/mmapmodule.c
+++ b/Modules/mmapmodule.c
@@ -129,7 +129,7 @@ mmap_object_dealloc(mmap_object *m_obj)
        }
 #endif /* UNIX */
 
-       PyObject_Del(m_obj);
+       m_obj->ob_type->tp_free((PyObject*)m_obj);
 }
 
 static PyObject *



I'll write a test for this issue and will attach a complete patch.
Sorry again.

./python Lib/test/test_mmap.py works with a debug build with this patch.

Committed as r60202. Thanks for the care!