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PEP 695 changed how class decorators are traced #104686
Description
Commit 24d8b88 ("gh-103763: Implement PEP 695 (#103764)") changed how nested class decorators are traced.
Example file nightly-20230518.py:
def decorator(arg):
def _dec(c):
return c
return _dec
@decorator(6)
@decorator(
len([8]),
)
class MyObject(
object
):
X = 13
a = 14Tracing with 3.12.0a7:
% python3.12 -m trace --trace nightly-20230518.py --- modulename: nightly-20230518, funcname: <module> nightly-20230518.py(1): def decorator(arg): nightly-20230518.py(6): @decorator(6) --- modulename: nightly-20230518, funcname: decorator nightly-20230518.py(2): def _dec(c): nightly-20230518.py(4): return _dec nightly-20230518.py(7): @decorator( nightly-20230518.py(8): len([8]), nightly-20230518.py(7): @decorator( --- modulename: nightly-20230518, funcname: decorator nightly-20230518.py(2): def _dec(c): nightly-20230518.py(4): return _dec nightly-20230518.py(10): class MyObject( <***** nightly-20230518.py(11): object nightly-20230518.py(10): class MyObject( --- modulename: nightly-20230518, funcname: MyObject nightly-20230518.py(6): @decorator(6) nightly-20230518.py(13): X = 13 nightly-20230518.py(7): @decorator( --- modulename: nightly-20230518, funcname: _dec nightly-20230518.py(3): return c nightly-20230518.py(6): @decorator(6) --- modulename: nightly-20230518, funcname: _dec nightly-20230518.py(3): return c nightly-20230518.py(10): class MyObject( nightly-20230518.py(14): a = 14
% python3.12 -c "import sys; print(sys.version)" 3.12.0a7 (main, Apr 5 2023, 05:51:58) [Clang 14.0.3 (clang-1403.0.22.14.1)]
Running with newer code:
% /usr/local/cpython/bin/python3 -m trace --trace nightly-20230518.py --- modulename: nightly-20230518, funcname: <module> nightly-20230518.py(1): def decorator(arg): nightly-20230518.py(6): @decorator(6) --- modulename: nightly-20230518, funcname: decorator nightly-20230518.py(2): def _dec(c): nightly-20230518.py(4): return _dec nightly-20230518.py(7): @decorator( nightly-20230518.py(8): len([8]), nightly-20230518.py(7): @decorator( --- modulename: nightly-20230518, funcname: decorator nightly-20230518.py(2): def _dec(c): nightly-20230518.py(4): return _dec nightly-20230518.py(6): @decorator(6) <***** nightly-20230518.py(11): object nightly-20230518.py(10): class MyObject( --- modulename: nightly-20230518, funcname: MyObject nightly-20230518.py(6): @decorator(6) nightly-20230518.py(13): X = 13 nightly-20230518.py(7): @decorator( --- modulename: nightly-20230518, funcname: _dec nightly-20230518.py(3): return c nightly-20230518.py(6): @decorator(6) --- modulename: nightly-20230518, funcname: _dec nightly-20230518.py(3): return c nightly-20230518.py(10): class MyObject( nightly-20230518.py(14): a = 14
% /usr/local/cpython/bin/python3 -c "import sys; print(sys.version)" 3.12.0a7+ (tags/v3.12.0a7-548-g24d8b88420:24d8b88420, May 20 2023, 06:39:38) [Clang 14.0.3 (clang-1403.0.22.14.1)]
The different lines are marked with <*****.
cc: @JelleZijlstra @markshannon
Activity
JelleZijlstra commented on May 20, 2023
In the disassembly I see that the instructions for creating the class are on a different (wrong) line:
main:
8 42 CALL 1 7 50 PUSH_NULL 52 LOAD_BUILD_CLASS 54 LOAD_CONST 3 (<code object MyObject at 0x104ea5e40, file "<dis>", line 7>) 56 MAKE_FUNCTION 0 58 LOAD_CONST 4 ('MyObject') 12 60 LOAD_NAME 2 (object)3.11:
8 54 PRECALL 1 58 CALL 1 11 68 PUSH_NULL 70 LOAD_BUILD_CLASS 72 LOAD_CONST 3 (<code object MyObject at 0x10536ef50, file "<dis>", line 7>) 74 MAKE_FUNCTION 0 76 LOAD_CONST 4 ('MyObject') 12 78 LOAD_NAME 2 (object)So presumably I put the wrong location somewhere in the compiler. I'll take a look.
pythongh-104686: Fix tracing for decorated classes
JelleZijlstra commented on May 20, 2023
Submitted a fix in #104708, thanks @nedbat for the early report!
gh-104686: Fix tracing for decorated classes (#104708)