Message356758
> However, that's still going to be clearer to most readers than writing
It is subjective. To me, j+1/j looks clearer than (j:=i*i)+1/j. In addition, the for-as-assignment idiom is more powerful in context of comprehensions, it allows to set an initial value. In any case I want to have a choice.
> OOC, rather than optimizing a fairly ugly use case, might another approach be to make walrus less leaky?
I think this ship is sailed. The semantic of the walrus operator is complex enough to make it even more complex by adding more special cases. Also, while the function-wide optimization of variables is possible, it much more complex problem than the proposed simple optimization.
> You should probably rerun your benchmarks though
$ ./python -m timeit -s 'a = list(range(1000))' -- '[y for x in a for y in [x]]'
Unpatched: 5000 loops, best of 5: 66.8 usec per loop
Patched: 10000 loops, best of 5: 21.5 usec per loop
$ ./python -m timeit -s 'a = list(range(1000))' -- '[x for x in a]'
20000 loops, best of 5: 17.8 usec per loop
Issue32925 reduce the difference, but it is still large (~12). |
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Date |
User |
Action |
Args |
2019-11-16 17:20:06 | serhiy.storchaka | set | recipients:
+ serhiy.storchaka, brett.cannon, rhettinger, ncoghlan, scoder, benjamin.peterson, steven.daprano, josh.r |
2019-11-16 17:20:06 | serhiy.storchaka | set | messageid: <1573924806.28.0.468425233193.issue32856@roundup.psfhosted.org> |
2019-11-16 17:20:06 | serhiy.storchaka | link | issue32856 messages |
2019-11-16 17:20:05 | serhiy.storchaka | create | |
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