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Diffstat (limited to 'Doc/whatsnew/3.9.rst')
| -rw-r--r-- | Doc/whatsnew/3.9.rst | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/Doc/whatsnew/3.9.rst b/Doc/whatsnew/3.9.rst index c040410..ec17984 100644 --- a/Doc/whatsnew/3.9.rst +++ b/Doc/whatsnew/3.9.rst @@ -315,6 +315,17 @@ case), and one used ``__VENV_NAME__`` instead. Optimizations ============= +* Optimized the idiom for assignment a temporary variable in comprehensions. + Now ``for y in [expr]`` in comprehensions is as fast as a simple assignment + ``y = expr``. For example: + + sums = [s for s in [0] for x in data for s in [s + x]] + + Unlike to the ``:=`` operator this idiom does not leak a variable to the + outer scope. + + (Contributed by Serhiy Storchaka in :issue:`32856`.) + Build and C API Changes ======================= |