<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<script type="text/javascript">
var _gaq = _gaq || [];
_gaq.push(['_setAccount', 'UA-3052036-8']);
_gaq.push(['_trackPageview']);
(function() {
var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true;
ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js';
var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s);
})();
</script>
<title>Logging Messages — Twiggy</title>
<link rel="stylesheet" href="_static/default.css" type="text/css" />
<link rel="stylesheet" href="_static/pygments.css" type="text/css" />
<script type="text/javascript">
var DOCUMENTATION_OPTIONS = {
URL_ROOT: '',
VERSION: '0.4.4',
COLLAPSE_INDEX: false,
FILE_SUFFIX: '.html',
HAS_SOURCE: true
};
</script>
<script type="text/javascript" src="_static/jquery.js"></script>
<script type="text/javascript" src="_static/underscore.js"></script>
<script type="text/javascript" src="_static/doctools.js"></script>
<link rel="search" type="application/opensearchdescription+xml"
title="Search within Twiggy"
href="_static/opensearch.xml"/>
<link rel="top" title="Twiggy" href="index.html" />
<link rel="next" title="Configuring Output" href="configuration.html" />
<link rel="prev" title="Twiggy: A Pythonic Logger" href="index.html" />
</head>
<body>
<div class="related">
<h3>Navigation</h3>
<ul>
<li class="right" style="margin-right: 10px">
<a href="genindex.html" title="General Index"
accesskey="I">index</a></li>
<li class="right" >
<a href="configuration.html" title="Configuring Output"
accesskey="N">next</a> |</li>
<li class="right" >
<a href="index.html" title="Twiggy: A Pythonic Logger"
accesskey="P">previous</a> |</li>
<li><a href="index.html">Twiggy v0.4.4 documentation</a> »</li>
</ul>
</div>
<div class="document">
<div class="documentwrapper">
<div class="bodywrapper">
<div class="body">
<div class="section" id="logging-messages">
<h1>Logging Messages<a class="headerlink" href="#logging-messages" title="Permalink to this headline">¶</a></h1>
<p>This part describes how user code can log messages with twiggy.</p>
<p>To get started quickly, use <a class="reference internal" href="api.html#twiggy.quickSetup" title="twiggy.quickSetup"><tt class="xref py py-func docutils literal"><span class="pre">quickSetup()</span></tt></a>.:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="gp">>>> </span><span class="kn">import</span> <span class="nn">twiggy</span>
<span class="gp">>>> </span><span class="n">twiggy</span><span class="o">.</span><span class="n">quickSetup</span><span class="p">()</span>
</pre></div>
</div>
<div class="admonition-see-also admonition seealso">
<p class="first admonition-title">See also</p>
<p class="last">Full details on <a class="reference internal" href="configuration.html"><em>Configuring Output</em></a>.</p>
</div>
<div class="section" id="the-magic-log">
<h2>The Magic log<a class="headerlink" href="#the-magic-log" title="Permalink to this headline">¶</a></h2>
<p>The main interface is the the magic <a class="reference internal" href="api.html#twiggy.log" title="twiggy.log"><tt class="xref py py-data docutils literal"><span class="pre">log</span></tt></a>.</p>
<div class="highlight-python"><div class="highlight"><pre><span class="gp">>>> </span><span class="kn">from</span> <span class="nn">twiggy</span> <span class="kn">import</span> <span class="n">log</span>
<span class="gp">>>> </span><span class="n">log</span>
<span class="go"><twiggy.logger.Logger object at 0x...></span>
</pre></div>
</div>
<p>It works out of the box, using typical <a class="reference internal" href="api.html#module-twiggy.levels" title="twiggy.levels"><tt class="xref py py-mod docutils literal"><span class="pre">levels</span></tt></a>. Arbitrary levels are <em>not</em> supported. Note that when logging, you never need to refer to any level object; just use the methods on the log.</p>
<div class="highlight-python"><div class="highlight"><pre><span class="gp">>>> </span><span class="n">log</span><span class="o">.</span><span class="n">debug</span><span class="p">(</span><span class="s">'You may not care'</span><span class="p">)</span>
<span class="go">DEBUG:You may not care</span>
<span class="gp">>>> </span><span class="n">log</span><span class="o">.</span><span class="n">error</span><span class="p">(</span><span class="s">'OMFG! Pants on fire!'</span><span class="p">)</span>
<span class="go">ERROR:OMFG! Pants on fire!</span>
</pre></div>
</div>
<p>The log can handle messages in several styles of <a class="reference internal" href="reference_guide.html#alternate-styles"><em>format strings</em></a>, defaulting to <a class="reference external" href="http://docs.python.org/library/string.html#format-string-syntax">new-style</a>.</p>
<div class="highlight-python"><div class="highlight"><pre><span class="gp">>>> </span><span class="n">log</span><span class="o">.</span><span class="n">info</span><span class="p">(</span><span class="s">'I wear {0} on my {where}'</span><span class="p">,</span> <span class="s">'pants'</span><span class="p">,</span> <span class="n">where</span><span class="o">=</span><span class="s">'legs'</span><span class="p">)</span>
<span class="go">INFO:I wear pants on my legs</span>
</pre></div>
</div>
<p>You can name your loggers.</p>
<div class="highlight-python"><div class="highlight"><pre><span class="gp">>>> </span><span class="n">mylog</span> <span class="o">=</span> <span class="n">log</span><span class="o">.</span><span class="n">name</span><span class="p">(</span><span class="s">'alfredo'</span><span class="p">)</span>
<span class="gp">>>> </span><span class="n">mylog</span><span class="o">.</span><span class="n">debug</span><span class="p">(</span><span class="s">'hello'</span><span class="p">)</span>
<span class="go">DEBUG:alfredo:hello</span>
</pre></div>
</div>
</div>
<div class="section" id="better-output">
<span id="id1"></span><h2>Better output<a class="headerlink" href="#better-output" title="Permalink to this headline">¶</a></h2>
<p>Twiggy’s default output strives to be user-friendly and to avoid pet peeves.</p>
<p>Newlines are suppressed by default; that can be turned off per-message.</p>
<div class="highlight-python"><div class="highlight"><pre><span class="gp">>>> </span><span class="n">log</span><span class="o">.</span><span class="n">info</span><span class="p">(</span><span class="s">'user</span><span class="se">\n</span><span class="s">input</span><span class="se">\n</span><span class="s">annoys</span><span class="se">\n</span><span class="s">us'</span><span class="p">)</span>
<span class="go">INFO:user\ninput\nannoys\nus</span>
<span class="gp">>>> </span><span class="n">log</span><span class="o">.</span><span class="n">options</span><span class="p">(</span><span class="n">suppress_newlines</span><span class="o">=</span><span class="bp">False</span><span class="p">)</span><span class="o">.</span><span class="n">info</span><span class="p">(</span><span class="s">'we</span><span class="se">\n</span><span class="s">deal'</span><span class="p">)</span>
<span class="go">INFO:we</span>
<span class="go">deal</span>
</pre></div>
</div>
<p>Exceptions are prefixed by <tt class="docutils literal"><span class="pre">TRACE</span></tt>. By default, <a class="reference internal" href="api.html#twiggy.logger.BaseLogger.trace" title="twiggy.logger.BaseLogger.trace"><tt class="xref py py-meth docutils literal"><span class="pre">tracing</span></tt></a> will use the current exception, but you can also pass an exc_info tuple.</p>
<div class="highlight-python"><div class="highlight"><pre><span class="gp">>>> </span><span class="k">try</span><span class="p">:</span>
<span class="gp">... </span> <span class="mi">1</span><span class="o">/</span><span class="mi">0</span>
<span class="gp">... </span><span class="k">except</span><span class="p">:</span>
<span class="gp">... </span> <span class="n">log</span><span class="o">.</span><span class="n">trace</span><span class="p">(</span><span class="s">'error'</span><span class="p">)</span><span class="o">.</span><span class="n">warning</span><span class="p">(</span><span class="s">'oh noes'</span><span class="p">)</span>
<span class="go">WARNING:oh noes</span>
<span class="go">TRACE Traceback (most recent call last):</span>
<span class="go">TRACE File "<doctest better-output[...]>", line 2, in <module></span>
<span class="go">TRACE ZeroDivisionError: integer division or modulo by zero</span>
</pre></div>
</div>
<div class="admonition-see-also admonition seealso">
<p class="first admonition-title">See also</p>
<p class="last"><a class="reference internal" href="api.html#folding-exceptions"><em>How to fold exceptions to a single line</em></a></p>
</div>
</div>
<div class="section" id="structured-logging">
<span id="id2"></span><h2>Structured Logging<a class="headerlink" href="#structured-logging" title="Permalink to this headline">¶</a></h2>
<p>I like this method chaining style a lot.</p>
<div class="highlight-python"><div class="highlight"><pre><span class="gp">>>> </span><span class="n">log</span><span class="o">.</span><span class="n">name</span><span class="p">(</span><span class="s">'benito'</span><span class="p">)</span><span class="o">.</span><span class="n">info</span><span class="p">(</span><span class="s">'hi there'</span><span class="p">)</span>
<span class="go">INFO:benito:hi there</span>
</pre></div>
</div>
<p>It makes <a class="reference internal" href="glossary.html#term-structured-logging"><em class="xref std std-term">structured logging</em></a> easy. In the past, fielded data was stuffed in the text of your message:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="gp">>>> </span><span class="n">log</span><span class="o">.</span><span class="n">info</span><span class="p">(</span><span class="s">'Going for a walk. path: {0} roads: {1}'</span><span class="p">,</span> <span class="s">"less traveled"</span><span class="p">,</span> <span class="mi">42</span><span class="p">)</span>
<span class="go">INFO:Going for a walk. path: less traveled roads: 42</span>
</pre></div>
</div>
<p>Instead, you can use <a class="reference internal" href="api.html#twiggy.logger.BaseLogger.fields" title="twiggy.logger.BaseLogger.fields"><tt class="xref py py-meth docutils literal"><span class="pre">fields()</span></tt></a> to add arbitrary key-value pairs. Output is easily parseable.</p>
<div class="highlight-python"><div class="highlight"><pre><span class="gp">>>> </span><span class="n">log</span><span class="o">.</span><span class="n">fields</span><span class="p">(</span><span class="n">path</span><span class="o">=</span><span class="s">"less traveled"</span><span class="p">,</span> <span class="n">roads</span><span class="o">=</span><span class="mi">42</span><span class="p">)</span><span class="o">.</span><span class="n">info</span><span class="p">(</span><span class="s">'Going for a walk'</span><span class="p">)</span>
<span class="go">INFO:path=less traveled:roads=42:Going for a walk</span>
</pre></div>
</div>
<p>The <a class="reference internal" href="api.html#twiggy.logger.BaseLogger.struct" title="twiggy.logger.BaseLogger.struct"><tt class="xref py py-meth docutils literal"><span class="pre">struct()</span></tt></a> is a short cut for <em>only</em> logging fields. This is great for runtime statistics gathering.</p>
<div class="highlight-python"><div class="highlight"><pre><span class="gp">>>> </span><span class="n">log</span><span class="o">.</span><span class="n">struct</span><span class="p">(</span><span class="n">paths</span><span class="o">=</span><span class="mi">42</span><span class="p">,</span> <span class="n">dolphins</span><span class="o">=</span><span class="s">'thankful'</span><span class="p">)</span>
<span class="go">INFO:dolphins=thankful:paths=42:</span>
</pre></div>
</div>
</div>
<div class="section" id="partial-binding">
<h2>Partial Binding<a class="headerlink" href="#partial-binding" title="Permalink to this headline">¶</a></h2>
<p>Each call to <a class="reference internal" href="api.html#twiggy.logger.BaseLogger.fields" title="twiggy.logger.BaseLogger.fields"><tt class="xref py py-meth docutils literal"><span class="pre">fields()</span></tt></a> or <a class="reference internal" href="api.html#twiggy.logger.BaseLogger.options" title="twiggy.logger.BaseLogger.options"><tt class="xref py py-meth docutils literal"><span class="pre">options()</span></tt></a> creates a new, independent log instance that inherits all of the data of the parent. This incremental binding can be useful for webapps.</p>
<div class="highlight-python"><div class="highlight"><pre><span class="gp">>>> </span><span class="c">## an application-level log</span>
<span class="gp">... </span><span class="n">webapp_log</span> <span class="o">=</span> <span class="n">log</span><span class="o">.</span><span class="n">name</span><span class="p">(</span><span class="s">"myblog"</span><span class="p">)</span>
<span class="gp">>>> </span><span class="c">## a log for the individual request</span>
<span class="gp">... </span><span class="n">current_request_log</span> <span class="o">=</span> <span class="n">webapp_log</span><span class="o">.</span><span class="n">fields</span><span class="p">(</span><span class="n">request_id</span><span class="o">=</span><span class="s">'12345'</span><span class="p">)</span>
<span class="gp">>>> </span><span class="n">current_request_log</span><span class="o">.</span><span class="n">fields</span><span class="p">(</span><span class="n">rows</span><span class="o">=</span><span class="mi">100</span><span class="p">,</span> <span class="n">user</span><span class="o">=</span><span class="s">'frank'</span><span class="p">)</span><span class="o">.</span><span class="n">info</span><span class="p">(</span><span class="s">'frobnicating database'</span><span class="p">)</span>
<span class="go">INFO:myblog:request_id=12345:rows=100:user=frank:frobnicating database</span>
<span class="gp">>>> </span><span class="n">current_request_log</span><span class="o">.</span><span class="n">fields</span><span class="p">(</span><span class="nb">bytes</span><span class="o">=</span><span class="mi">5678</span><span class="p">)</span><span class="o">.</span><span class="n">info</span><span class="p">(</span><span class="s">'sending page over tubes'</span><span class="p">)</span>
<span class="go">INFO:myblog:bytes=5678:request_id=12345:sending page over tubes</span>
<span class="gp">>>> </span><span class="c">## a log for a different request</span>
<span class="gp">... </span><span class="n">another_log</span> <span class="o">=</span> <span class="n">webapp_log</span><span class="o">.</span><span class="n">fields</span><span class="p">(</span><span class="n">request_id</span><span class="o">=</span><span class="s">'67890'</span><span class="p">)</span>
<span class="gp">>>> </span><span class="n">another_log</span><span class="o">.</span><span class="n">debug</span><span class="p">(</span><span class="s">'Client connected'</span><span class="p">)</span>
<span class="go">DEBUG:myblog:request_id=67890:Client connected</span>
</pre></div>
</div>
<p>Chained style is awesome. It allows you to create complex yet parsable log messages in a concise way.</p>
<div class="highlight-python"><div class="highlight"><pre><span class="gp">>>> </span><span class="n">log</span><span class="o">.</span><span class="n">name</span><span class="p">(</span><span class="s">'donjuan'</span><span class="p">)</span><span class="o">.</span><span class="n">fields</span><span class="p">(</span><span class="n">pants</span><span class="o">=</span><span class="s">'sexy'</span><span class="p">)</span><span class="o">.</span><span class="n">info</span><span class="p">(</span><span class="s">"hello, {who} want to {what}?"</span><span class="p">,</span> <span class="n">who</span><span class="o">=</span><span class="s">'ladies'</span><span class="p">,</span> <span class="n">what</span><span class="o">=</span><span class="s">'dance'</span><span class="p">)</span>
<span class="go">INFO:donjuan:pants=sexy:hello, ladies want to dance?</span>
</pre></div>
</div>
</div>
<div class="section" id="sample-output">
<h2>Sample Output<a class="headerlink" href="#sample-output" title="Permalink to this headline">¶</a></h2>
<p id="sample-file-output">Routed to a <a class="reference internal" href="api.html#twiggy.outputs.FileOutput" title="twiggy.outputs.FileOutput"><tt class="xref py py-obj docutils literal"><span class="pre">file</span></tt></a>, the above produces the following:</p>
<div class="highlight-python"><pre>2010-03-28T14:23:34Z:DEBUG:You may not care
2010-03-28T14:23:34Z:ERROR:OMFG! Pants on fire!
2010-03-28T14:23:34Z:INFO:I like bikes
2010-03-28T14:23:34Z:INFO:I wear pants on my legs
2010-03-28T14:23:34Z:DEBUG:alfredo:hello
2010-03-28T14:23:34Z:INFO:user\ninput\nannoys\nus
2010-03-28T14:23:34Z:INFO:we
deal
2010-03-28T14:23:34Z:WARNING:oh noes
TRACE Traceback (most recent call last):
TRACE File "<doctest better-output[...]>", line 35, in <module>
TRACE ZeroDivisionError: integer division or modulo by zero
2010-03-28T14:23:34Z:INFO:benito:hi there
2010-03-28T14:23:34Z:INFO:Going for a walk. path: less traveled roads: 42
2010-03-28T14:23:34Z:INFO:path=less traveled:roads=42:Going for a walk
2010-03-28T14:23:34Z:INFO:dolphins=thankful:paths=42:
2010-03-28T14:23:34Z:INFO:myblog:request_id=12345:rows=100:user=frank:frobnicating database
2010-03-28T14:23:34Z:INFO:myblog:bytes=5678:request_id=12345:sending page over tubes
2010-03-28T14:23:34Z:INFO:myblog:request_id=67890:Client connected
2010-03-28T14:23:34Z:INFO:donjuan:pants=sexy:hello, ladies want to dance?
2010-03-28T14:23:34Z:INFO:myblog:request_id=12345:rows=100:user=frank:frobnicating database
2010-03-28T14:23:34Z:INFO:myblog:bytes=5678:request_id=12345:sending page over tubes
2010-03-28T14:23:34Z:DEBUG:myblog:request_id=67890:Client connected</pre>
</div>
</div>
</div>
</div>
</div>
</div>
<div class="sphinxsidebar">
<div class="sphinxsidebarwrapper">
<p class="logo"><a href="index.html">
<img class="logo" src="_static/twig_sidebar.jpg" alt="Logo"/>
</a></p>
<h3><a href="index.html">Table Of Contents</a></h3>
<ul>
<li><a class="reference internal" href="#">Logging Messages</a><ul>
<li><a class="reference internal" href="#the-magic-log">The Magic log</a></li>
<li><a class="reference internal" href="#better-output">Better output</a></li>
<li><a class="reference internal" href="#structured-logging">Structured Logging</a></li>
<li><a class="reference internal" href="#partial-binding">Partial Binding</a></li>
<li><a class="reference internal" href="#sample-output">Sample Output</a></li>
</ul>
</li>
</ul>
<h4>Previous topic</h4>
<p class="topless"><a href="index.html"
title="previous chapter">Twiggy: A Pythonic Logger</a></p>
<h4>Next topic</h4>
<p class="topless"><a href="configuration.html"
title="next chapter">Configuring Output</a></p>
<h3>This Page</h3>
<ul class="this-page-menu">
<li><a href="_sources/logging.txt"
rel="nofollow">Show Source</a></li>
</ul>
<div id="searchbox" style="display: none">
<h3>Quick search</h3>
<form class="search" action="search.html" method="get">
<input type="text" name="q" size="18" />
<input type="submit" value="Go" />
<input type="hidden" name="check_keywords" value="yes" />
<input type="hidden" name="area" value="default" />
</form>
<p class="searchtip" style="font-size: 90%">
Enter search terms or a module, class or function name.
</p>
</div>
<script type="text/javascript">$('#searchbox').show(0);</script>
</div>
</div>
<div class="clearer"></div>
</div>
<div class="related">
<h3>Navigation</h3>
<ul>
<li class="right" style="margin-right: 10px">
<a href="genindex.html" title="General Index"
>index</a></li>
<li class="right" >
<a href="configuration.html" title="Configuring Output"
>next</a> |</li>
<li class="right" >
<a href="index.html" title="Twiggy: A Pythonic Logger"
>previous</a> |</li>
<li><a href="index.html">Twiggy v0.4.4 documentation</a> »</li>
</ul>
</div>
<div class="footer">
© Copyright 2010, <a href="http://i.wearpants.org">Peter Fein</a>.
Last updated on Jul 10, 2012.
Created using <a href="http://sphinx.pocoo.org/">Sphinx</a> 1.0.7.
</div>
</body>
</html>
distrib
>
Mandriva
>
2010.1
>
x86_64
>
media
>
contrib-backports
>
by-pkgid
>
e15f173f36ff245dfb6d502e2debb9a7
>
files
>
62
