Jelle Zijlstra added the comment: The reason for this behavior is that the trace function is called whenever execution in the bytecode jumps to a new source line. See ceval.c line 4440 or so:
/* If the last instruction falls at the start of a line or if it represents a jump backwards, update the frame's line number and call the trace function. */ Running dis.dis on x in the example file shows that the bytecode for returning None is assigned to the "pass" line. I think the bug here is really with the line number assignment in the bytecode, not with the tracing, but I don't see an obvious way to fix it. ---------- nosy: +Jelle Zijlstra _______________________________________ Python tracker <rep...@bugs.python.org> <http://bugs.python.org/issue13548> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com