bpo-32856: Optimize the idiom for assignment in comprehensions. #5695
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Now `for y in [expr]` in comprehensions is so fast as a simple assignment `y = expr`.
serhiy-storchaka
changed the title
1st1
reviewed
Feb 16, 2018
| break; | ||
| case Tuple_kind: | ||
| elts = gen->iter->v.Tuple.elts; | ||
| break; |
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How about we handle for x in {a} too?
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This will change the behavior if a is not hashable.
1st1
reviewed
Feb 16, 2018
| @@ -0,0 +1,3 @@ | |||
| Optimized the idiom for assignment a temporary variable in comprehensions. | |||
| Now ``for y in [expr]`` in comprehensions is so fast as a simple assignment | |||
| ``y = expr``. | |||
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Please update the NEWS entry with some benchmark results.
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I'm not sure what should I provide. The optimized code always is the part of complex comprehension expression.
cpitclaudel
reviewed
Feb 22, 2018
Lib/test/test_dictcomps.py
Outdated
| @@ -81,6 +81,17 @@ def test_illegal_assignment(self): | |||
| compile("{x: y for y, x in ((1, 2), (3, 4))} += 5", "<test>", | |||
| "exec") | |||
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| def test_assignment_idiom_in_comprehesions(self): | |||
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Now
for y in [expr]in comprehensions is so fast as a simple assignmenty = expr.https://bugs.python.org/issue32856