:mod:`trace` --- Trace or track Python statement execution ========================================================== .. module:: trace :synopsis: Trace or track Python statement execution. The :mod:`trace` module allows you to trace program execution, generate annotated statement coverage listings, print caller/callee relationships and list functions executed during a program run. It can be used in another program or from the command line. .. _trace-cli: Command Line Usage ------------------ The :mod:`trace` module can be invoked from the command line. It can be as simple as :: python -m trace --count somefile.py ... The above will generate annotated listings of all Python modules imported during the execution of :file:`somefile.py`. The following command-line arguments are supported: :option:`--trace`, :option:`-t` Display lines as they are executed. :option:`--count`, :option:`-c` Produce a set of annotated listing files upon program completion that shows how many times each statement was executed. :option:`--report`, :option:`-r` Produce an annotated list from an earlier program run that used the :option:`--count` and :option:`--file` arguments. :option:`--no-report`, :option:`-R` Do not generate annotated listings. This is useful if you intend to make several runs with :option:`--count` then produce a single set of annotated listings at the end. :option:`--listfuncs`, :option:`-l` List the functions executed by running the program. :option:`--trackcalls`, :option:`-T` Generate calling relationships exposed by running the program. :option:`--file`, :option:`-f` Name a file containing (or to contain) counts. :option:`--coverdir`, :option:`-C` Name a directory in which to save annotated listing files. :option:`--missing`, :option:`-m` When generating annotated listings, mark lines which were not executed with '``>>>>>>``'. :option:`--summary`, :option:`-s` When using :option:`--count` or :option:`--report`, write a brief summary to stdout for each file processed. :option:`--ignore-module` Accepts comma separated list of module names. Ignore each of the named module and its submodules (if it is a package). May be given multiple times. :option:`--ignore-dir` Ignore all modules and packages in the named directory and subdirectories (multiple directories can be joined by os.pathsep). May be given multiple times. .. _trace-api: Programming Interface --------------------- .. class:: Trace([count=1[, trace=1[, countfuncs=0[, countcallers=0[, ignoremods=()[, ignoredirs=()[, infile=None[, outfile=None[, timing=False]]]]]]]]]) Create an object to trace execution of a single statement or expression. All parameters are optional. *count* enables counting of line numbers. *trace* enables line execution tracing. *countfuncs* enables listing of the functions called during the run. *countcallers* enables call relationship tracking. *ignoremods* is a list of modules or packages to ignore. *ignoredirs* is a list of directories whose modules or packages should be ignored. *infile* is the file from which to read stored count information. *outfile* is a file in which to write updated count information. *timing* enables a timestamp relative to when tracing was started to be displayed. .. method:: Trace.run(cmd) Run *cmd* under control of the Trace object with the current tracing parameters. .. method:: Trace.runctx(cmd[, globals=None[, locals=None]]) Run *cmd* under control of the Trace object with the current tracing parameters in the defined global and local environments. If not defined, *globals* and *locals* default to empty dictionaries. .. method:: Trace.runfunc(func, *args, **kwds) Call *func* with the given arguments under control of the :class:`Trace` object with the current tracing parameters. This is a simple example showing the use of this module:: import sys import trace # create a Trace object, telling it what to ignore, and whether to # do tracing or line-counting or both. tracer = trace.Trace( ignoredirs=[sys.prefix, sys.exec_prefix], trace=0, count=1) # run the new command using the given tracer tracer.run('main()') # make a report, placing output in /tmp r = tracer.results() r.write_results(show_missing=True, coverdir="/tmp")