1 

     2 :mod:`trace` --- Trace or track Python statement execution

     3 ==========================================================

     4 

     5 .. module:: trace

     6    :synopsis: Trace or track Python statement execution.

     7 

     8 

     9 The :mod:`trace` module allows you to trace program execution, generate

    10 annotated statement coverage listings, print caller/callee relationships and

    11 list functions executed during a program run.  It can be used in another program

    12 or from the command line.

    13 

    14 

    15 .. _trace-cli:

    16 

    17 Command Line Usage

    18 ------------------

    19 

    20 The :mod:`trace` module can be invoked from the command line.  It can be as

    21 simple as ::

    22 

    23    python -m trace --count somefile.py ...

    24 

    25 The above will generate annotated listings of all Python modules imported during

    26 the execution of :file:`somefile.py`.

    27 

    28 The following command-line arguments are supported:

    29 

    30 :option:`--trace`, :option:`-t`

    31    Display lines as they are executed.

    32 

    33 :option:`--count`, :option:`-c`

    34    Produce a set of  annotated listing files upon program completion that shows how

    35    many times each statement was executed.

    36 

    37 :option:`--report`, :option:`-r`

    38    Produce an annotated list from an earlier program run that used the

    39    :option:`--count` and :option:`--file` arguments.

    40 

    41 :option:`--no-report`, :option:`-R`

    42    Do not generate annotated listings.  This is useful if you intend to make

    43    several runs with :option:`--count` then produce a single set of annotated

    44    listings at the end.

    45 

    46 :option:`--listfuncs`, :option:`-l`

    47    List the functions executed by running the program.

    48 

    49 :option:`--trackcalls`, :option:`-T`

    50    Generate calling relationships exposed by running the program.

    51 

    52 :option:`--file`, :option:`-f`

    53    Name a file containing (or to contain) counts.

    54 

    55 :option:`--coverdir`, :option:`-C`

    56    Name a directory in which to save annotated listing files.

    57 

    58 :option:`--missing`, :option:`-m`

    59    When generating annotated listings, mark lines which were not executed with

    60    '``>>>>>>``'.

    61 

    62 :option:`--summary`, :option:`-s`

    63    When using :option:`--count` or :option:`--report`, write a brief summary to

    64    stdout for each file processed.

    65 

    66 :option:`--ignore-module`

    67    Accepts comma separated list of module names. Ignore each of the named

    68    module and its submodules (if it is a package).  May be given 

    69    multiple times.

    70 

    71 :option:`--ignore-dir`

    72    Ignore all modules and packages in the named directory and subdirectories

    73    (multiple directories can be joined by os.pathsep).  May be given multiple

    74    times. 

    75 

    76 

    77 .. _trace-api:

    78 

    79 Programming Interface

    80 ---------------------

    81 

    82 

    83 .. class:: Trace([count=1[, trace=1[, countfuncs=0[, countcallers=0[, ignoremods=()[, ignoredirs=()[, infile=None[, outfile=None[, timing=False]]]]]]]]])

    84 

    85    Create an object to trace execution of a single statement or expression. All

    86    parameters are optional.  *count* enables counting of line numbers. *trace*

    87    enables line execution tracing.  *countfuncs* enables listing of the functions

    88    called during the run.  *countcallers* enables call relationship tracking.

    89    *ignoremods* is a list of modules or packages to ignore.  *ignoredirs* is a list

    90    of directories whose modules or packages should be ignored.  *infile* is the

    91    file from which to read stored count information.  *outfile* is a file in which

    92    to write updated count information. *timing* enables a timestamp relative

    93    to when tracing was started to be displayed.

    94 

    95 

    96 .. method:: Trace.run(cmd)

    97 

    98    Run *cmd* under control of the Trace object with the current tracing parameters.

    99 

   100 

   101 .. method:: Trace.runctx(cmd[, globals=None[, locals=None]])

   102 

   103    Run *cmd* under control of the Trace object with the current tracing parameters

   104    in the defined global and local environments.  If not defined, *globals* and

   105    *locals* default to empty dictionaries.

   106 

   107 

   108 .. method:: Trace.runfunc(func, *args, **kwds)

   109 

   110    Call *func* with the given arguments under control of the :class:`Trace` object

   111    with the current tracing parameters.

   112 

   113 This is a simple example showing the use of this module::

   114 

   115    import sys

   116    import trace

   117 

   118    # create a Trace object, telling it what to ignore, and whether to

   119    # do tracing or line-counting or both.

   120    tracer = trace.Trace(

   121        ignoredirs=[sys.prefix, sys.exec_prefix],

   122        trace=0,

   123        count=1)

   124 

   125    # run the new command using the given tracer

   126    tracer.run('main()')

   127 

   128    # make a report, placing output in /tmp

   129    r = tracer.results()

   130    r.write_results(show_missing=True, coverdir="/tmp")

   131