Edit File: trace.txt
:mod:`trace` --- Trace or track Python statement execution ========================================================== .. module:: trace :synopsis: Trace or track Python statement execution. **Source code:** :source:`Lib/trace.py` -------------- 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 -C . somefile.py ... The above will execute :file:`somefile.py` and generate annotated listings of all Python modules imported during the execution into the current directory. .. program:: trace .. cmdoption:: --help Display usage and exit. .. cmdoption:: --version Display the version of the module and exit. Main options ^^^^^^^^^^^^ At least one of the following options must be specified when invoking :mod:`trace`. The :option:`--listfuncs <-l>` option is mutually exclusive with the :option:`--trace <-t>` and :option:`--counts <-c>` options . When :option:`--listfuncs <-l>` is provided, neither :option:`--counts <-c>` nor :option:`--trace <-t>` are accepted, and vice versa. .. program:: trace .. cmdoption:: -c, --count Produce a set of annotated listing files upon program completion that shows how many times each statement was executed. See also :option:`--coverdir <-C>`, :option:`--file <-f>` and :option:`--no-report <-R>` below. .. cmdoption:: -t, --trace Display lines as they are executed. .. cmdoption:: -l, --listfuncs Display the functions executed by running the program. .. cmdoption:: -r, --report Produce an annotated list from an earlier program run that used the :option:`--count <-c>` and :option:`--file <-f>` option. This does not execute any code. .. cmdoption:: -T, --trackcalls Display the calling relationships exposed by running the program. Modifiers ^^^^^^^^^ .. program:: trace .. cmdoption:: -f, --file=<file> Name of a file to accumulate counts over several tracing runs. Should be used with the :option:`--count <-c>` option. .. cmdoption:: -C, --coverdir=<dir> Directory where the report files go. The coverage report for ``package.module`` is written to file :file:`{dir}/{package}/{module}.cover`. .. cmdoption:: -m, --missing When generating annotated listings, mark lines which were not executed with ``>>>>>>``. .. cmdoption:: -s, --summary When using :option:`--count <-c>` or :option:`--report <-r>`, write a brief summary to stdout for each file processed. .. cmdoption:: -R, --no-report Do not generate annotated listings. This is useful if you intend to make several runs with :option:`--count <-c>`, and then produce a single set of annotated listings at the end. .. cmdoption:: -g, --timing Prefix each line with the time since the program started. Only used while tracing. Filters ^^^^^^^ These options may be repeated multiple times. .. program:: trace .. cmdoption:: --ignore-module=<mod> Ignore each of the given module names and its submodules (if it is a package). The argument can be a list of names separated by a comma. .. cmdoption:: --ignore-dir=<dir> Ignore all modules and packages in the named directory and subdirectories. The argument can be a list of directories separated by :data:`os.pathsep`. .. _trace-api: Programmatic 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 name of the file from which to read stored count information. *outfile* is the name of the file in which to write updated count information. *timing* enables a timestamp relative to when tracing was started to be displayed. .. method:: run(cmd) Execute the command and gather statistics from the execution with the current tracing parameters. *cmd* must be a string or code object, suitable for passing into :func:`exec`. .. method:: runctx(cmd, globals=None, locals=None) Execute the command and gather statistics from the execution with the current tracing parameters, in the defined global and local environments. If not defined, *globals* and *locals* default to empty dictionaries. .. method:: runfunc(func, *args, **kwds) Call *func* with the given arguments under control of the :class:`Trace` object with the current tracing parameters. .. method:: results() Return a :class:`CoverageResults` object that contains the cumulative results of all previous calls to ``run``, ``runctx`` and ``runfunc`` for the given :class:`Trace` instance. Does not reset the accumulated trace results. .. class:: CoverageResults A container for coverage results, created by :meth:`Trace.results`. Should not be created directly by the user. .. method:: update(other) Merge in data from another :class:`CoverageResults` object. .. method:: write_results([show_missing=True[, summary=False[, coverdir=None]]]) Write coverage results. Set *show_missing* to show lines that had no hits. Set *summary* to include in the output the coverage summary per module. *coverdir* specifies the directory into which the coverage result files will be output. If ``None``, the results for each source file are placed in its directory. A simple example demonstrating the use of the programmatic interface:: 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 the current directory r = tracer.results() r.write_results(show_missing=True, coverdir=".")