Author ysj.ray
Recipients eggy, ysj.ray
Date 2010-11-24.14:08:08
SpamBayes Score 1.54987e-13
Marked as misclassified No
Message-id <1290607692.77.0.548477514822.issue7238@psf.upfronthosting.co.za>
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Content
It's not a bug. What happens is like this:

1, You set trace function using sys.settrace(tracer).
2, When the following func() is called, tracer is called with a "call" event, so the trace function in PyThreadState is set to NULL since "sys.settrace(None)" is execute, but since the return value is a valid local trace function, the frame of called function("func()") has its local trace function.
3, The called function("func()") executes, though its frame has a local trace function, but it will not be executed since PyThreadState->c_tracefunc is NULL. When you get f_lineno from frame, you get the not refreshed f_lineno value but not the dynamically computed lineno, as the f_lineno's getter function said:
    if(f->f_trace)
        return f->f_lineno;
    else
        return PyCode_Addr2Line(f->f_code, f->f_lasti);

   Here because your frame's local trace function is not executed, the f_lineno is not refreshed.

4, When the second time func() calls, there is no global trace function. Each time you get the f_lineno, it uses PyCode_Addr2Line() to get the dynamically computed line number.


I think this situation is so rarely that the doc saying "f_lineno is 
the current line number of the frame" is correct.
History
Date User Action Args
2010-11-24 14:08:12ysj.raysetrecipients: + ysj.ray, eggy
2010-11-24 14:08:12ysj.raysetmessageid: <1290607692.77.0.548477514822.issue7238@psf.upfronthosting.co.za>
2010-11-24 14:08:08ysj.raylinkissue7238 messages
2010-11-24 14:08:08ysj.raycreate