python's sys.settrace won't trace builtin functions -

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• python's sys.settrace won't create c_call events 1 answer

i've been using sys.settrace function write tracer program, working great except doesn't seem called built-in functions, open('filename.txt'). behavior doesn't seem documented, i'm not sure if i'm doing wrong or if expected behavior. using doug hellmann's "trace_calls_and_returns" code here tracing function.

if can't settrace, there way trace calls open()? don't want use linux's strace, it'll run whole program (not part want trace) , won't show python line numbers/file names, etc. other option considered monkey-patching open function through wrapper, like:

import traceback, __builtin__ def wrapped_open(*arg,**kw):          print 'open called'          traceback.print_stack()          f = __builtin__.open(*arg,**kw)          return f  open = wrapped_open  

but seemed brittle me.

could suggest better way of doing this?

you won't able trace compiled code imported python, , open() not pure python, it's c binding cpython part of python distribution.

so way you'll have trace within open() go strace or equivalent, in ways, beyond python can introspect of himself.