Message122915
| Author |
pitrou |
| Recipients |
catlee, davide.rizzo, eric.araujo, georg.brandl, jhylton, orsenthil, pitrou, rcoyner, rhettinger, xuanji |
| Date |
2010年11月30日.16:37:46 |
| SpamBayes Score |
2.792325e-06 |
| Marked as misclassified |
No |
| Message-id |
<1291135067.89.0.39569474795.issue3243@psf.upfronthosting.co.za> |
| In-reply-to |
| Content |
Answering to myself, sorry. memoryview() does return the right answer of whether the object supports the buffer interface, *however* it doesn't mean the len() will be right. For example, take an array.array of ints:
>>> memoryview(array.array("I", [1,2,3]))
<memory at 0x1cf5720>
>>> len(array.array("I", [1,2,3]))
3
>>> len(memoryview(array.array("I", [1,2,3])))
3
>>> len(bytes(array.array("I", [1,2,3])))
12
len() returns 3 but the number of bytes written out by sendall() will really be 12...
*However*, the right len can be calculated using the memoryview:
>>> m = memoryview(array.array("I", [1,2,3]))
>>> len(m) * m.itemsize
12
(without actually converting to a bytes object, so all this is cheap even for very large buffers) |
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