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After years, better integration between the old and new buffer interfaces was finally sneaked in as a bug fix. You can now call `memoryview(some_buffer)` and it

After years, better integration between the old and new buffer interfaces was finally sneaked in as a bug fix. You can now call `memoryview(some_buffer)` and it'll DTRT. The whole buffers situation is a depressing mess.

chubot 14y ago
I haven't played around with it, but how did it get to be a mess? As I recall it has historically been for NumPy.
pekk 14y ago
Since you have been voted to the top of the thread for this comment, can you be more concrete on your complaint?
- masklinn 14y ago
  See http://bugs.python.org/issue10211 http://bugs.python.org/issue10211 Basically, Python has the "buffer" object which is a 0-copy view of some memory area (lets an object expose itself as a bytes array of sorts). It's always been plagued with a number of issues. In Python 3, `buffer` was removed and replaced with `memoryview`, which was backported to Python 2.7. But in said Python 2.7, `buffer` and `memoryview` both exist and fill very similar need so e.g. older libraries will likely return a buffer which newer code will want to use as a memoryview. No such luck, they're not compatible. 2.7.4 fixes that so you can get a memoryview from a buffer.
cbsmith 14y ago
I too would like more details on this. 2.7.3 already had memoryview objects IIRC, though I found them almost as frustrating to work with as the 2.6.x world of not having them. What really changed in 2.7.4?
- masklinn 14y ago
  In 2.7.3, you can create a buffer which is the "old" buffer interface: http://docs.python.org/2/library/functions.html#buffer http://docs.python.org/2/library/functions.html#buffer And you can create a memoryview which is the "new" and more flexible buffer interface: http://docs.python.org/2/library/stdtypes.html#typememoryview http://docs.python.org/2/library/stdtypes.html#typememoryvie... You can get a buffer of a string: >>> buffer("foo") <read-only buffer for 0x1005a5ee0, size -1, offset 0 at 0x10054f270> and a view of a string: >>> memoryview("foo") <memory at 0x100574d60> but when you get this unhelpful and really stupid result: >>> memoryview(buffer("foo")) Traceback (most recent call last): File "<stdin>", line 1, in <module> TypeError: cannot make memory view because object does not have the buffer interface 2.7.4 fixed this so it actually works and you can get a memoryview out of an old buffer.
  - cbsmith 14y ago
    Awesome, that was precisely the kind of annoyance I remember.

chubot 14y ago

I haven't played around with it, but how did it get to be a mess? As I recall it has historically been for NumPy.

pekk 14y ago

Since you have been voted to the top of the thread for this comment, can you be more concrete on your complaint?

masklinn 14y ago
See http://bugs.python.org/issue10211 http://bugs.python.org/issue10211 Basically, Python has the "buffer" object which is a 0-copy view of some memory area (lets an object expose itself as a bytes array of sorts). It's always been plagued with a number of issues. In Python 3, `buffer` was removed and replaced with `memoryview`, which was backported to Python 2.7. But in said Python 2.7, `buffer` and `memoryview` both exist and fill very similar need so e.g. older libraries will likely return a buffer which newer code will want to use as a memoryview. No such luck, they're not compatible. 2.7.4 fixes that so you can get a memoryview from a buffer.

cbsmith 14y ago

I too would like more details on this. 2.7.3 already had memoryview objects IIRC, though I found them almost as frustrating to work with as the 2.6.x world of not having them. What really changed in 2.7.4?

masklinn 14y ago
In 2.7.3, you can create a buffer which is the "old" buffer interface: http://docs.python.org/2/library/functions.html#buffer http://docs.python.org/2/library/functions.html#buffer And you can create a memoryview which is the "new" and more flexible buffer interface: http://docs.python.org/2/library/stdtypes.html#typememoryview http://docs.python.org/2/library/stdtypes.html#typememoryvie... You can get a buffer of a string: >>> buffer("foo") <read-only buffer for 0x1005a5ee0, size -1, offset 0 at 0x10054f270> and a view of a string: >>> memoryview("foo") <memory at 0x100574d60> but when you get this unhelpful and really stupid result: >>> memoryview(buffer("foo")) Traceback (most recent call last): File "<stdin>", line 1, in <module> TypeError: cannot make memory view because object does not have the buffer interface 2.7.4 fixed this so it actually works and you can get a memoryview out of an old buffer.
- cbsmith 14y ago
  Awesome, that was precisely the kind of annoyance I remember.