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href="#filters">Filters</a></li>112</ul>113</li>114<li><a class="reference internal" href="#programmatic-interface">Programmatic Interface</a></li>115</ul>116</li>117</ul>118 119  </div>120  <div>121    <h4>Previous topic</h4>122    <p class="topless"><a href="timeit.html"123                          title="previous chapter"><code class="xref py py-mod docutils literal notranslate"><span class="pre">timeit</span></code> — Measure execution time of small code snippets</a></p>124  </div>125  <div>126    <h4>Next topic</h4>127    <p class="topless"><a href="tracemalloc.html"128                          title="next chapter"><code class="xref py py-mod docutils literal notranslate"><span class="pre">tracemalloc</span></code> — Trace memory allocations</a></p>129  </div>130  <script>131    document.addEventListener('DOMContentLoaded', () => {132        const title = document.querySelector('meta[property="og:title"]').content;133        const elements = 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class="headerlink" href="#module-trace" title="Link to this heading">¶</a></h1>225<p><strong>Source code:</strong> <a class="extlink-source reference external" href="https://github.com/python/cpython/tree/main/Lib/trace.py">Lib/trace.py</a></p>226<hr class="docutils" />227<p>The <code class="xref py py-mod docutils literal notranslate"><span class="pre">trace</span></code> module allows you to trace program execution, generate228annotated statement coverage listings, print caller/callee relationships and229list functions executed during a program run.  It can be used in another program230or from the command line.</p>231<div class="admonition seealso">232<p class="admonition-title">See also</p>233<dl class="simple">234<dt><a class="reference external" href="https://coverage.readthedocs.io/">Coverage.py</a></dt><dd><p>A popular third-party coverage tool that provides HTML235output along with advanced features such as branch coverage.</p>236</dd>237</dl>238</div>239<section id="command-line-usage">240<span id="trace-cli"></span><h2>Command-Line Usage<a class="headerlink" href="#command-line-usage" title="Link to this heading">¶</a></h2>241<p>The <code class="xref py py-mod docutils literal notranslate"><span class="pre">trace</span></code> module can be invoked from the command line.  It can be as242simple as</p>243<div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="n">python</span> <span class="o">-</span><span class="n">m</span> <span class="n">trace</span> <span class="o">--</span><span class="n">count</span> <span class="o">-</span><span class="n">C</span> <span class="o">.</span> <span class="n">somefile</span><span class="o">.</span><span class="n">py</span> <span class="o">...</span>244</pre></div>245</div>246<p>The above will execute <code class="file docutils literal notranslate"><span class="pre">somefile.py</span></code> and generate annotated listings of247all Python modules imported during the execution into the current directory.</p>248<dl class="std option">249<dt class="sig sig-object std" id="cmdoption-trace-help">250<span class="sig-name descname"><span class="pre">--help</span></span><span class="sig-prename descclassname"></span><a class="headerlink" href="#cmdoption-trace-help" title="Link to this definition">¶</a></dt>251<dd><p>Display usage and exit.</p>252</dd></dl>253 254<dl class="std option">255<dt class="sig sig-object std" id="cmdoption-trace-version">256<span class="sig-name descname"><span class="pre">--version</span></span><span class="sig-prename descclassname"></span><a class="headerlink" href="#cmdoption-trace-version" title="Link to this definition">¶</a></dt>257<dd><p>Display the version of the module and exit.</p>258</dd></dl>259 260<div class="versionadded">261<p><span class="versionmodified added">Added in version 3.8: </span>Added <code class="docutils literal notranslate"><span class="pre">--module</span></code> option that allows running an executable module.</p>262</div>263<section id="main-options">264<h3>Main options<a class="headerlink" href="#main-options" title="Link to this heading">¶</a></h3>265<p>At least one of the following options must be specified when invoking266<code class="xref py py-mod docutils literal notranslate"><span class="pre">trace</span></code>.  The <a class="reference internal" href="#cmdoption-trace-l"><code class="xref std std-option docutils literal notranslate"><span class="pre">--listfuncs</span></code></a> option is mutually exclusive with267the <a class="reference internal" href="#cmdoption-trace-t"><code class="xref std std-option docutils literal notranslate"><span class="pre">--trace</span></code></a> and <a class="reference internal" href="#cmdoption-trace-c"><code class="xref std std-option docutils literal notranslate"><span class="pre">--count</span></code></a> options. When268<code class="xref std std-option docutils literal notranslate"><span class="pre">--listfuncs</span></code> is provided, neither <code class="xref std std-option docutils literal notranslate"><span class="pre">--count</span></code> nor269<code class="xref std std-option docutils literal notranslate"><span class="pre">--trace</span></code> are accepted, and vice versa.</p>270<dl class="std option">271<dt class="sig sig-object std" id="cmdoption-trace-c">272<span id="cmdoption-trace-count"></span><span class="sig-name descname"><span class="pre">-c</span></span><span class="sig-prename descclassname"></span><span class="sig-prename descclassname"><span class="pre">,</span> </span><span class="sig-name descname"><span class="pre">--count</span></span><span class="sig-prename descclassname"></span><a class="headerlink" href="#cmdoption-trace-c" title="Link to this definition">¶</a></dt>273<dd><p>Produce a set of annotated listing files upon program completion that shows274how many times each statement was executed.  See also275<a class="reference internal" href="#cmdoption-trace-C"><code class="xref std std-option docutils literal notranslate"><span class="pre">--coverdir</span></code></a>, <a class="reference internal" href="#cmdoption-trace-f"><code class="xref std std-option docutils literal notranslate"><span class="pre">--file</span></code></a> and276<a class="reference internal" href="#cmdoption-trace-R"><code class="xref std std-option docutils literal notranslate"><span class="pre">--no-report</span></code></a> below.</p>277</dd></dl>278 279<dl class="std option">280<dt class="sig sig-object std" id="cmdoption-trace-t">281<span id="cmdoption-trace-trace"></span><span class="sig-name descname"><span class="pre">-t</span></span><span class="sig-prename descclassname"></span><span class="sig-prename descclassname"><span class="pre">,</span> </span><span class="sig-name descname"><span class="pre">--trace</span></span><span class="sig-prename descclassname"></span><a class="headerlink" href="#cmdoption-trace-t" title="Link to this definition">¶</a></dt>282<dd><p>Display lines as they are executed.</p>283</dd></dl>284 285<dl class="std option">286<dt class="sig sig-object std" id="cmdoption-trace-l">287<span id="cmdoption-trace-listfuncs"></span><span class="sig-name descname"><span class="pre">-l</span></span><span class="sig-prename descclassname"></span><span class="sig-prename descclassname"><span class="pre">,</span> </span><span class="sig-name descname"><span class="pre">--listfuncs</span></span><span class="sig-prename descclassname"></span><a class="headerlink" href="#cmdoption-trace-l" title="Link to this definition">¶</a></dt>288<dd><p>Display the functions executed by running the program.</p>289</dd></dl>290 291<dl class="std option">292<dt class="sig sig-object std" id="cmdoption-trace-r">293<span id="cmdoption-trace-report"></span><span class="sig-name descname"><span class="pre">-r</span></span><span class="sig-prename descclassname"></span><span class="sig-prename descclassname"><span class="pre">,</span> </span><span class="sig-name descname"><span class="pre">--report</span></span><span class="sig-prename descclassname"></span><a class="headerlink" href="#cmdoption-trace-r" title="Link to this definition">¶</a></dt>294<dd><p>Produce an annotated list from an earlier program run that used the295<a class="reference internal" href="#cmdoption-trace-c"><code class="xref std std-option docutils literal notranslate"><span class="pre">--count</span></code></a> and <a class="reference internal" href="#cmdoption-trace-f"><code class="xref std std-option docutils literal notranslate"><span class="pre">--file</span></code></a> option.  This does not296execute any code.</p>297</dd></dl>298 299<dl class="std option">300<dt class="sig sig-object std" id="cmdoption-trace-T">301<span id="cmdoption-trace-trackcalls"></span><span class="sig-name descname"><span class="pre">-T</span></span><span class="sig-prename descclassname"></span><span class="sig-prename descclassname"><span class="pre">,</span> </span><span class="sig-name descname"><span class="pre">--trackcalls</span></span><span class="sig-prename descclassname"></span><a class="headerlink" href="#cmdoption-trace-T" title="Link to this definition">¶</a></dt>302<dd><p>Display the calling relationships exposed by running the program.</p>303</dd></dl>304 305</section>306<section id="modifiers">307<h3>Modifiers<a class="headerlink" href="#modifiers" title="Link to this heading">¶</a></h3>308<dl class="std option">309<dt class="sig sig-object std" id="cmdoption-trace-f">310<span id="cmdoption-trace-file"></span><span class="sig-name descname"><span class="pre">-f</span></span><span class="sig-prename descclassname"></span><span class="sig-prename descclassname"><span class="pre">,</span> </span><span class="sig-name descname"><span class="pre">--file</span></span><span class="sig-prename descclassname"><span class="pre">=&lt;file&gt;</span></span><a class="headerlink" href="#cmdoption-trace-f" title="Link to this definition">¶</a></dt>311<dd><p>Name of a file to accumulate counts over several tracing runs.  Should be312used with the <a class="reference internal" href="#cmdoption-trace-c"><code class="xref std std-option docutils literal notranslate"><span class="pre">--count</span></code></a> option.</p>313</dd></dl>314 315<dl class="std option">316<dt class="sig sig-object std" id="cmdoption-trace-C">317<span id="cmdoption-trace-coverdir"></span><span class="sig-name descname"><span class="pre">-C</span></span><span class="sig-prename descclassname"></span><span class="sig-prename descclassname"><span class="pre">,</span> </span><span class="sig-name descname"><span class="pre">--coverdir</span></span><span class="sig-prename descclassname"><span class="pre">=&lt;dir&gt;</span></span><a class="headerlink" href="#cmdoption-trace-C" title="Link to this definition">¶</a></dt>318<dd><p>Directory where the report files go.  The coverage report for319<code class="docutils literal notranslate"><span class="pre">package.module</span></code> is written to file <code class="file docutils literal notranslate"><em><span class="pre">dir</span></em><span class="pre">/</span><em><span class="pre">package</span></em><span class="pre">/</span><em><span class="pre">module</span></em><span class="pre">.cover</span></code>.</p>320</dd></dl>321 322<dl class="std option">323<dt class="sig sig-object std" id="cmdoption-trace-m">324<span id="cmdoption-trace-missing"></span><span class="sig-name descname"><span class="pre">-m</span></span><span class="sig-prename descclassname"></span><span class="sig-prename descclassname"><span class="pre">,</span> </span><span class="sig-name descname"><span class="pre">--missing</span></span><span class="sig-prename descclassname"></span><a class="headerlink" href="#cmdoption-trace-m" title="Link to this definition">¶</a></dt>325<dd><p>When generating annotated listings, mark lines which were not executed with326<code class="docutils literal notranslate"><span class="pre">&gt;&gt;&gt;&gt;&gt;&gt;</span></code>.</p>327</dd></dl>328 329<dl class="std option">330<dt class="sig sig-object std" id="cmdoption-trace-s">331<span id="cmdoption-trace-summary"></span><span class="sig-name descname"><span class="pre">-s</span></span><span class="sig-prename descclassname"></span><span class="sig-prename descclassname"><span class="pre">,</span> </span><span class="sig-name descname"><span class="pre">--summary</span></span><span class="sig-prename descclassname"></span><a class="headerlink" href="#cmdoption-trace-s" title="Link to this definition">¶</a></dt>332<dd><p>When using <a class="reference internal" href="#cmdoption-trace-c"><code class="xref std std-option docutils literal notranslate"><span class="pre">--count</span></code></a> or <a class="reference internal" href="#cmdoption-trace-r"><code class="xref std std-option docutils literal notranslate"><span class="pre">--report</span></code></a>, write a brief333summary to stdout for each file processed.</p>334</dd></dl>335 336<dl class="std option">337<dt class="sig sig-object std" id="cmdoption-trace-R">338<span id="cmdoption-trace-no-report"></span><span class="sig-name descname"><span class="pre">-R</span></span><span class="sig-prename descclassname"></span><span class="sig-prename descclassname"><span class="pre">,</span> </span><span class="sig-name descname"><span class="pre">--no-report</span></span><span class="sig-prename descclassname"></span><a class="headerlink" href="#cmdoption-trace-R" title="Link to this definition">¶</a></dt>339<dd><p>Do not generate annotated listings.  This is useful if you intend to make340several runs with <a class="reference internal" href="#cmdoption-trace-c"><code class="xref std std-option docutils literal notranslate"><span class="pre">--count</span></code></a>, and then produce a single set of341annotated listings at the end.</p>342</dd></dl>343 344<dl class="std option">345<dt class="sig sig-object std" id="cmdoption-trace-g">346<span id="cmdoption-trace-timing"></span><span class="sig-name descname"><span class="pre">-g</span></span><span class="sig-prename descclassname"></span><span class="sig-prename descclassname"><span class="pre">,</span> </span><span class="sig-name descname"><span class="pre">--timing</span></span><span class="sig-prename descclassname"></span><a class="headerlink" href="#cmdoption-trace-g" title="Link to this definition">¶</a></dt>347<dd><p>Prefix each line with the time since the program started.  Only used while348tracing.</p>349</dd></dl>350 351</section>352<section id="filters">353<h3>Filters<a class="headerlink" href="#filters" title="Link to this heading">¶</a></h3>354<p>These options may be repeated multiple times.</p>355<dl class="std option">356<dt class="sig sig-object std" id="cmdoption-trace-ignore-module">357<span class="sig-name descname"><span class="pre">--ignore-module</span></span><span class="sig-prename descclassname"><span class="pre">=&lt;mod&gt;</span></span><a class="headerlink" href="#cmdoption-trace-ignore-module" title="Link to this definition">¶</a></dt>358<dd><p>Ignore each of the given module names and its submodules (if it is a359package).  The argument can be a list of names separated by a comma.</p>360</dd></dl>361 362<dl class="std option">363<dt class="sig sig-object std" id="cmdoption-trace-ignore-dir">364<span class="sig-name descname"><span class="pre">--ignore-dir</span></span><span class="sig-prename descclassname"><span class="pre">=&lt;dir&gt;</span></span><a class="headerlink" href="#cmdoption-trace-ignore-dir" title="Link to this definition">¶</a></dt>365<dd><p>Ignore all modules and packages in the named directory and subdirectories.366The argument can be a list of directories separated by <a class="reference internal" href="os.html#os.pathsep" title="os.pathsep"><code class="xref py py-data docutils literal notranslate"><span class="pre">os.pathsep</span></code></a>.</p>367</dd></dl>368 369</section>370</section>371<section id="programmatic-interface">372<span id="trace-api"></span><h2>Programmatic Interface<a class="headerlink" href="#programmatic-interface" title="Link to this heading">¶</a></h2>373<dl class="py class">374<dt class="sig sig-object py" id="trace.Trace">375<em class="property"><span class="k"><span class="pre">class</span></span><span class="w"> </span></em><span class="sig-prename descclassname"><span class="pre">trace.</span></span><span class="sig-name descname"><span class="pre">Trace</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">count</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">1</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">trace</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">1</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">countfuncs</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">0</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">countcallers</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">0</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">ignoremods</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">()</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">ignoredirs</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">()</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">infile</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">None</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">outfile</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">None</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">timing</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">False</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#trace.Trace" title="Link to this definition">¶</a></dt>376<dd><p>Create an object to trace execution of a single statement or expression.  All377parameters are optional.  <em>count</em> enables counting of line numbers.  <em>trace</em>378enables line execution tracing.  <em>countfuncs</em> enables listing of the379functions called during the run.  <em>countcallers</em> enables call relationship380tracking.  <em>ignoremods</em> is a list of modules or packages to ignore.381<em>ignoredirs</em> is a list of directories whose modules or packages should be382ignored.  <em>infile</em> is the name of the file from which to read stored count383information.  <em>outfile</em> is the name of the file in which to write updated384count information.  <em>timing</em> enables a timestamp relative to when tracing was385started to be displayed.</p>386<dl class="py method">387<dt class="sig sig-object py" id="trace.Trace.run">388<span class="sig-name descname"><span class="pre">run</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">cmd</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#trace.Trace.run" title="Link to this definition">¶</a></dt>389<dd><p>Execute the command and gather statistics from the execution with390the current tracing parameters.  <em>cmd</em> must be a string or code object,391suitable for passing into <a class="reference internal" href="functions.html#exec" title="exec"><code class="xref py py-func docutils literal notranslate"><span class="pre">exec()</span></code></a>.</p>392</dd></dl>393 394<dl class="py method">395<dt class="sig sig-object py" id="trace.Trace.runctx">396<span class="sig-name descname"><span class="pre">runctx</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">cmd</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">globals</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">None</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">locals</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">None</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#trace.Trace.runctx" title="Link to this definition">¶</a></dt>397<dd><p>Execute the command and gather statistics from the execution with the398current tracing parameters, in the defined global and local399environments.  If not defined, <em>globals</em> and <em>locals</em> default to empty400dictionaries.</p>401</dd></dl>402 403<dl class="py method">404<dt class="sig sig-object py" id="trace.Trace.runfunc">405<span class="sig-name descname"><span class="pre">runfunc</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">func</span></span></em>, <em class="sig-param"><span class="positional-only-separator o"><abbr title="Positional-only parameter separator (PEP 570)"><span class="pre">/</span></abbr></span></em>, <em class="sig-param"><span class="o"><span class="pre">*</span></span><span class="n"><span class="pre">args</span></span></em>, <em class="sig-param"><span class="o"><span class="pre">**</span></span><span class="n"><span class="pre">kwds</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#trace.Trace.runfunc" title="Link to this definition">¶</a></dt>406<dd><p>Call <em>func</em> with the given arguments under control of the <code class="xref py py-class docutils literal notranslate"><span class="pre">Trace</span></code>407object with the current tracing parameters.</p>408</dd></dl>409 410<dl class="py method">411<dt class="sig sig-object py" id="trace.Trace.results">412<span class="sig-name descname"><span class="pre">results</span></span><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#trace.Trace.results" title="Link to this definition">¶</a></dt>413<dd><p>Return a <a class="reference internal" href="#trace.CoverageResults" title="trace.CoverageResults"><code class="xref py py-class docutils literal notranslate"><span class="pre">CoverageResults</span></code></a> object that contains the cumulative414results of all previous calls to <code class="docutils literal notranslate"><span class="pre">run</span></code>, <code class="docutils literal notranslate"><span class="pre">runctx</span></code> and <code class="docutils literal notranslate"><span class="pre">runfunc</span></code>415for the given <code class="xref py py-class docutils literal notranslate"><span class="pre">Trace</span></code> instance.  Does not reset the accumulated416trace results.</p>417</dd></dl>418 419</dd></dl>420 421<dl class="py class">422<dt class="sig sig-object py" id="trace.CoverageResults">423<em class="property"><span class="k"><span class="pre">class</span></span><span class="w"> </span></em><span class="sig-prename descclassname"><span class="pre">trace.</span></span><span class="sig-name descname"><span class="pre">CoverageResults</span></span><a class="headerlink" href="#trace.CoverageResults" title="Link to this definition">¶</a></dt>424<dd><p>A container for coverage results, created by <a class="reference internal" href="#trace.Trace.results" title="trace.Trace.results"><code class="xref py py-meth docutils literal notranslate"><span class="pre">Trace.results()</span></code></a>.  Should425not be created directly by the user.</p>426<dl class="py method">427<dt class="sig sig-object py" id="trace.CoverageResults.update">428<span class="sig-name descname"><span class="pre">update</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">other</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#trace.CoverageResults.update" title="Link to this definition">¶</a></dt>429<dd><p>Merge in data from another <code class="xref py py-class docutils literal notranslate"><span class="pre">CoverageResults</span></code> object.</p>430</dd></dl>431 432<dl class="py method">433<dt class="sig sig-object py" id="trace.CoverageResults.write_results">434<span class="sig-name descname"><span class="pre">write_results</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">show_missing</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">True</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">summary</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">False</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">coverdir</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">None</span></span></em>, <em class="sig-param"><span class="keyword-only-separator o"><abbr title="Keyword-only parameters separator (PEP 3102)"><span class="pre">*</span></abbr></span></em>, <em class="sig-param"><span class="n"><span class="pre">ignore_missing_files</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">False</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#trace.CoverageResults.write_results" title="Link to this definition">¶</a></dt>435<dd><p>Write coverage results.  Set <em>show_missing</em> to show lines that had no436hits.  Set <em>summary</em> to include in the output the coverage summary per437module.  <em>coverdir</em> specifies the directory into which the coverage438result files will be output.  If <code class="docutils literal notranslate"><span class="pre">None</span></code>, the results for each source439file are placed in its directory.</p>440<p>If <em>ignore_missing_files</em> is <code class="docutils literal notranslate"><span class="pre">True</span></code>, coverage counts for files that no441longer exist are silently ignored. Otherwise, a missing file will442raise a <a class="reference internal" href="exceptions.html#FileNotFoundError" title="FileNotFoundError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">FileNotFoundError</span></code></a>.</p>443<div class="versionchanged">444<p><span class="versionmodified changed">Changed in version 3.13: </span>Added <em>ignore_missing_files</em> parameter.</p>445</div>446</dd></dl>447 448</dd></dl>449 450<p>A simple example demonstrating the use of the programmatic interface:</p>451<div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="kn">import</span><span class="w"> </span><span class="nn">sys</span>452<span class="kn">import</span><span class="w"> </span><span class="nn">trace</span>453 454<span class="c1"># create a Trace object, telling it what to ignore, and whether to</span>455<span class="c1"># do tracing or line-counting or both.</span>456<span class="n">tracer</span> <span class="o">=</span> <span class="n">trace</span><span class="o">.</span><span class="n">Trace</span><span class="p">(</span>457    <span class="n">ignoredirs</span><span class="o">=</span><span class="p">[</span><span class="n">sys</span><span class="o">.</span><span class="n">prefix</span><span class="p">,</span> <span class="n">sys</span><span class="o">.</span><span class="n">exec_prefix</span><span class="p">],</span>458    <span class="n">trace</span><span class="o">=</span><span class="mi">0</span><span class="p">,</span>459    <span class="n">count</span><span class="o">=</span><span class="mi">1</span><span class="p">)</span>460 461<span class="c1"># run the new command using the given tracer</span>462<span class="n">tracer</span><span class="o">.</span><span class="n">run</span><span class="p">(</span><span class="s1">&#39;main()&#39;</span><span class="p">)</span>463 464<span class="c1"># make a report, placing output in the current directory</span>465<span class="n">r</span> <span class="o">=</span> <span class="n">tracer</span><span class="o">.</span><span class="n">results</span><span class="p">()</span>466<span class="n">r</span><span class="o">.</span><span class="n">write_results</span><span class="p">(</span><span class="n">show_missing</span><span class="o">=</span><span class="kc">True</span><span class="p">,</span> <span class="n">coverdir</span><span class="o">=</span><span class="s2">&quot;.&quot;</span><span class="p">)</span>467</pre></div>468</div>469</section>470</section>471 472 473            <div class="clearer"></div>474          </div>475        </div>476      </div>477      <div class="sphinxsidebar" role="navigation" aria-label="Main">478        <div class="sphinxsidebarwrapper">479  <div>480    <h3><a href="../contents.html">Table of Contents</a></h3>481    <ul>482<li><a class="reference internal" href="#"><code class="xref py py-mod docutils literal notranslate"><span class="pre">trace</span></code> — Trace or track Python statement execution</a><ul>483<li><a class="reference internal" href="#command-line-usage">Command-Line Usage</a><ul>484<li><a class="reference internal" href="#main-options">Main options</a></li>485<li><a class="reference internal" href="#modifiers">Modifiers</a></li>486<li><a class="reference internal" href="#filters">Filters</a></li>487</ul>488</li>489<li><a class="reference internal" href="#programmatic-interface">Programmatic Interface</a></li>490</ul>491</li>492</ul>493 494  </div>495  <div>496    <h4>Previous topic</h4>497    <p class="topless"><a href="timeit.html"498                          title="previous chapter"><code class="xref py py-mod docutils literal notranslate"><span class="pre">timeit</span></code> — Measure execution time of small code snippets</a></p>499  </div>500  <div>501    <h4>Next topic</h4>502    <p class="topless"><a href="tracemalloc.html"503                          title="next chapter"><code class="xref py py-mod docutils literal notranslate"><span 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