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| author | Serhiy Storchaka <storchaka@gmail.com> | 2020-02-12 10:18:59 (GMT) |
|---|---|---|
| committer | GitHub <noreply@github.com> | 2020-02-12 10:18:59 (GMT) |
| commit | 8c579b1cc86053473eb052b76327279476740c9b (patch) | |
| tree | bc99d5f52e1330500216512d1064c2f341b64d89 /Lib/test/test_listcomps.py | |
| parent | 0cc6b5e559b8303b18fdd56c2befd900fe7b5e35 (diff) | |
| download | cpython-8c579b1cc86053473eb052b76327279476740c9b.zip cpython-8c579b1cc86053473eb052b76327279476740c9b.tar.gz cpython-8c579b1cc86053473eb052b76327279476740c9b.tar.bz2 | |
bpo-32856: Optimize the assignment idiom in comprehensions. (GH-16814)
Now `for y in [expr]` in comprehensions is as fast as a simple
assignment `y = expr`.
Diffstat (limited to 'Lib/test/test_listcomps.py')
| -rw-r--r-- | Lib/test/test_listcomps.py | 16 |
1 files changed, 16 insertions, 0 deletions
diff --git a/Lib/test/test_listcomps.py b/Lib/test/test_listcomps.py index ddb169f..62b3319 100644 --- a/Lib/test/test_listcomps.py +++ b/Lib/test/test_listcomps.py @@ -16,6 +16,22 @@ Test nesting with the inner expression dependent on the outer >>> [(i,j) for i in range(4) for j in range(i)] [(1, 0), (2, 0), (2, 1), (3, 0), (3, 1), (3, 2)] +Test the idiom for temporary variable assignment in comprehensions. + + >>> [j*j for i in range(4) for j in [i+1]] + [1, 4, 9, 16] + >>> [j*k for i in range(4) for j in [i+1] for k in [j+1]] + [2, 6, 12, 20] + >>> [j*k for i in range(4) for j, k in [(i+1, i+2)]] + [2, 6, 12, 20] + +Not assignment + + >>> [i*i for i in [*range(4)]] + [0, 1, 4, 9] + >>> [i*i for i in (*range(4),)] + [0, 1, 4, 9] + Make sure the induction variable is not exposed >>> i = 20 |