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Logging
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gto76 committed Aug 19, 2024
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46 changes: 23 additions & 23 deletions README.md
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Expand Up @@ -2234,35 +2234,35 @@ match <object/expression>:
Logging
-------
```python
import logging
import logging as log
```

```python
logging.basicConfig(filename=<path>, level='DEBUG') # Configures the root logger (see Setup).
logging.debug/info/warning/error/critical(<str>) # Logs to the root logger.
<Logger> = logging.getLogger(__name__) # Logger named after the module.
<Logger>.<level>(<str>) # Logs to the logger.
<Logger>.exception(<str>) # Error() that appends caught exception.
log.basicConfig(filename=<path>, level='DEBUG') # Configures the root logger (see Setup).
log.debug/info/warning/error/critical(<str>) # Logs to the root logger.
<Logger> = log.getLogger(__name__) # Logger named after the module.
<Logger>.<level>(<str>) # Logs to the logger.
<Logger>.exception(<str>) # Error() that appends caught exception.
```

### Setup
```python
logging.basicConfig(
filename=None, # Logs to stderr or appends to file.
format='%(levelname)s:%(name)s:%(message)s', # Add '%(asctime)s' for local datetime.
level=logging.WARNING, # Drops messages with lower priority.
handlers=[logging.StreamHandler(sys.stderr)] # Uses FileHandler if filename is set.
log.basicConfig(
filename=None, # Logs to stderr or appends to file.
format='%(levelname)s:%(name)s:%(message)s', # Add '%(asctime)s' for local datetime.
level=log.WARNING, # Drops messages with lower priority.
handlers=[log.StreamHandler(sys.stderr)] # Uses FileHandler if filename is set.
)
```

```python
<Formatter> = logging.Formatter('<format>') # Creates a Formatter.
<Handler> = logging.FileHandler(<path>, mode='a') # Creates a Handler. Also `encoding=None`.
<Handler>.setFormatter(<Formatter>) # Adds Formatter to the Handler.
<Handler>.setLevel(<int/str>) # Processes all messages by default.
<Logger>.addHandler(<Handler>) # Adds Handler to the Logger.
<Logger>.setLevel(<int/str>) # What is sent to its/ancestors' handlers.
<Logger>.propagate = <bool> # Cuts off ancestors' handlers if False.
<Formatter> = log.Formatter('<format>') # Creates a Formatter.
<Handler> = log.FileHandler(<path>, mode='a') # Creates a Handler. Also `encoding=None`.
<Handler>.setFormatter(<Formatter>) # Adds Formatter to the Handler.
<Handler>.setLevel(<int/str>) # Processes all messages by default.
<Logger>.addHandler(<Handler>) # Adds Handler to the Logger.
<Logger>.setLevel(<int/str>) # What is sent to its/ancestors' handlers.
<Logger>.propagate = <bool> # Cuts off ancestors' handlers if False.
```
* **Parent logger can be specified by naming the child logger `'<parent>.<name>'`.**
* **If logger doesn't have a set level it inherits it from the first ancestor that does.**
Expand All @@ -2271,13 +2271,13 @@ logging.basicConfig(

#### Creates a logger that writes all messages to file and sends them to the root's handler that prints warnings or higher:
```python
>>> logger = logging.getLogger('my_module')
>>> handler = logging.FileHandler('test.log', encoding='utf-8')
>>> handler.setFormatter(logging.Formatter('%(asctime)s %(levelname)s:%(name)s:%(message)s'))
>>> logger = log.getLogger('my_module')
>>> handler = log.FileHandler('test.log', encoding='utf-8')
>>> handler.setFormatter(log.Formatter('%(asctime)s %(levelname)s:%(name)s:%(message)s'))
>>> logger.addHandler(handler)
>>> logger.setLevel('DEBUG')
>>> logging.basicConfig()
>>> logging.root.handlers[0].setLevel('WARNING')
>>> log.basicConfig()
>>> log.root.handlers[0].setLevel('WARNING')
>>> logger.critical('Running out of disk space.')
CRITICAL:my_module:Running out of disk space.
>>> print(open('test.log').read())
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52 changes: 26 additions & 26 deletions index.html
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Expand Up @@ -54,7 +54,7 @@

<body>
<header>
<aside>August 18, 2024</aside>
<aside>August 19, 2024</aside>
<a href="https://gto76.github.io" rel="author">Jure Šorn</a>
</header>

Expand Down Expand Up @@ -1834,48 +1834,48 @@ <h3 id="format-2">Format</h3><div><h4 id="forstandardtypesizesandmanualalignment
<span class="hljs-string">'README.md is a readme file that belongs to user gto.'</span>
</code></pre></div>

<div><h2 id="logging"><a href="#logging" name="logging">#</a>Logging</h2><pre><code class="python language-python hljs"><span class="hljs-keyword">import</span> logging
<div><h2 id="logging"><a href="#logging" name="logging">#</a>Logging</h2><pre><code class="python language-python hljs"><span class="hljs-keyword">import</span> logging <span class="hljs-keyword">as</span> log
</code></pre></div>

<pre><code class="python language-python hljs">logging.basicConfig(filename=&lt;path&gt;, level=<span class="hljs-string">'DEBUG'</span>) <span class="hljs-comment"># Configures the root logger (see Setup).</span>
logging.debug/info/warning/error/critical(&lt;str&gt;) <span class="hljs-comment"># Logs to the root logger.</span>
&lt;Logger&gt; = logging.getLogger(__name__) <span class="hljs-comment"># Logger named after the module.</span>
&lt;Logger&gt;.&lt;level&gt;(&lt;str&gt;) <span class="hljs-comment"># Logs to the logger.</span>
&lt;Logger&gt;.exception(&lt;str&gt;) <span class="hljs-comment"># Error() that appends caught exception.</span>
<pre><code class="python language-python hljs">log.basicConfig(filename=&lt;path&gt;, level=<span class="hljs-string">'DEBUG'</span>) <span class="hljs-comment"># Configures the root logger (see Setup).</span>
log.debug/info/warning/error/critical(&lt;str&gt;) <span class="hljs-comment"># Logs to the root logger.</span>
&lt;Logger&gt; = log.getLogger(__name__) <span class="hljs-comment"># Logger named after the module.</span>
&lt;Logger&gt;.&lt;level&gt;(&lt;str&gt;) <span class="hljs-comment"># Logs to the logger.</span>
&lt;Logger&gt;.exception(&lt;str&gt;) <span class="hljs-comment"># Error() that appends caught exception.</span>
</code></pre>
<div><h3 id="setup">Setup</h3><pre><code class="python language-python hljs">logging.basicConfig(
filename=<span class="hljs-keyword">None</span>, <span class="hljs-comment"># Logs to stderr or appends to file.</span>
format=<span class="hljs-string">'%(levelname)s:%(name)s:%(message)s'</span>, <span class="hljs-comment"># Add '%(asctime)s' for local datetime.</span>
level=logging.WARNING, <span class="hljs-comment"># Drops messages with lower priority.</span>
handlers=[logging.StreamHandler(sys.stderr)] <span class="hljs-comment"># Uses FileHandler if filename is set.</span>
<div><h3 id="setup">Setup</h3><pre><code class="python language-python hljs">log.basicConfig(
filename=<span class="hljs-keyword">None</span>, <span class="hljs-comment"># Logs to stderr or appends to file.</span>
format=<span class="hljs-string">'%(levelname)s:%(name)s:%(message)s'</span>, <span class="hljs-comment"># Add '%(asctime)s' for local datetime.</span>
level=log.WARNING, <span class="hljs-comment"># Drops messages with lower priority.</span>
handlers=[log.StreamHandler(sys.stderr)] <span class="hljs-comment"># Uses FileHandler if filename is set.</span>
)
</code></pre></div>

<pre><code class="python language-python hljs">&lt;Formatter&gt; = logging.Formatter(<span class="hljs-string">'&lt;format&gt;'</span>) <span class="hljs-comment"># Creates a Formatter.</span>
&lt;Handler&gt; = logging.FileHandler(&lt;path&gt;, mode=<span class="hljs-string">'a'</span>) <span class="hljs-comment"># Creates a Handler. Also `encoding=None`.</span>
&lt;Handler&gt;.setFormatter(&lt;Formatter&gt;) <span class="hljs-comment"># Adds Formatter to the Handler.</span>
&lt;Handler&gt;.setLevel(&lt;int/str&gt;) <span class="hljs-comment"># Processes all messages by default.</span>
&lt;Logger&gt;.addHandler(&lt;Handler&gt;) <span class="hljs-comment"># Adds Handler to the Logger.</span>
&lt;Logger&gt;.setLevel(&lt;int/str&gt;) <span class="hljs-comment"># What is sent to its/ancestors' handlers.</span>
&lt;Logger&gt;.propagate = &lt;bool&gt; <span class="hljs-comment"># Cuts off ancestors' handlers if False.</span>
<pre><code class="python language-python hljs">&lt;Formatter&gt; = log.Formatter(<span class="hljs-string">'&lt;format&gt;'</span>) <span class="hljs-comment"># Creates a Formatter.</span>
&lt;Handler&gt; = log.FileHandler(&lt;path&gt;, mode=<span class="hljs-string">'a'</span>) <span class="hljs-comment"># Creates a Handler. Also `encoding=None`.</span>
&lt;Handler&gt;.setFormatter(&lt;Formatter&gt;) <span class="hljs-comment"># Adds Formatter to the Handler.</span>
&lt;Handler&gt;.setLevel(&lt;int/str&gt;) <span class="hljs-comment"># Processes all messages by default.</span>
&lt;Logger&gt;.addHandler(&lt;Handler&gt;) <span class="hljs-comment"># Adds Handler to the Logger.</span>
&lt;Logger&gt;.setLevel(&lt;int/str&gt;) <span class="hljs-comment"># What is sent to its/ancestors' handlers.</span>
&lt;Logger&gt;.propagate = &lt;bool&gt; <span class="hljs-comment"># Cuts off ancestors' handlers if False.</span>
</code></pre>
<ul>
<li><strong>Parent logger can be specified by naming the child logger <code class="python hljs"><span class="hljs-string">'&lt;parent&gt;.&lt;name&gt;'</span></code>.</strong></li>
<li><strong>If logger doesn't have a set level it inherits it from the first ancestor that does.</strong></li>
<li><strong>Formatter also accepts: pathname, filename, funcName, lineno, thread and process.</strong></li>
<li><strong>A <code class="python hljs"><span class="hljs-string">'handlers.RotatingFileHandler'</span></code> creates and deletes log files based on 'maxBytes' and 'backupCount' arguments.</strong></li>
</ul>
<div><h4 id="createsaloggerthatwritesallmessagestofileandsendsthemtotherootshandlerthatprintswarningsorhigher">Creates a logger that writes all messages to file and sends them to the root's handler that prints warnings or higher:</h4><pre><code class="python language-python hljs"><span class="hljs-meta">&gt;&gt;&gt; </span>logger = logging.getLogger(<span class="hljs-string">'my_module'</span>)
<span class="hljs-meta">&gt;&gt;&gt; </span>handler = logging.FileHandler(<span class="hljs-string">'test.log'</span>, encoding=<span class="hljs-string">'utf-8'</span>)
<span class="hljs-meta">&gt;&gt;&gt; </span>handler.setFormatter(logging.Formatter(<span class="hljs-string">'%(asctime)s %(levelname)s:%(name)s:%(message)s'</span>))
<div><h4 id="createsaloggerthatwritesallmessagestofileandsendsthemtotherootshandlerthatprintswarningsorhigher">Creates a logger that writes all messages to file and sends them to the root's handler that prints warnings or higher:</h4><pre><code class="python language-python hljs"><span class="hljs-meta">&gt;&gt;&gt; </span>logger = log.getLogger(<span class="hljs-string">'my_module'</span>)
<span class="hljs-meta">&gt;&gt;&gt; </span>handler = log.FileHandler(<span class="hljs-string">'test.log'</span>, encoding=<span class="hljs-string">'utf-8'</span>)
<span class="hljs-meta">&gt;&gt;&gt; </span>handler.setFormatter(log.Formatter(<span class="hljs-string">'%(asctime)s %(levelname)s:%(name)s:%(message)s'</span>))
<span class="hljs-meta">&gt;&gt;&gt; </span>logger.addHandler(handler)
<span class="hljs-meta">&gt;&gt;&gt; </span>logger.setLevel(<span class="hljs-string">'DEBUG'</span>)
<span class="hljs-meta">&gt;&gt;&gt; </span>logging.basicConfig()
<span class="hljs-meta">&gt;&gt;&gt; </span>logging.root.handlers[<span class="hljs-number">0</span>].setLevel(<span class="hljs-string">'WARNING'</span>)
<span class="hljs-meta">&gt;&gt;&gt; </span>log.basicConfig()
<span class="hljs-meta">&gt;&gt;&gt; </span>log.root.handlers[<span class="hljs-number">0</span>].setLevel(<span class="hljs-string">'WARNING'</span>)
<span class="hljs-meta">&gt;&gt;&gt; </span>logger.critical(<span class="hljs-string">'Running out of disk space.'</span>)
CRITICAL:my_module:Running out of disk space.
<span class="hljs-meta">&gt;&gt;&gt; </span>print(open(<span class="hljs-string">'test.log'</span>).read())
2023-02-07 23:21:01,430 CRITICAL:my_module:Running out of disk space.
<span class="hljs-number">2023</span><span class="hljs-number">-02</span><span class="hljs-number">-07</span> <span class="hljs-number">23</span>:<span class="hljs-number">21</span>:<span class="hljs-number">01</span>,<span class="hljs-number">430</span> CRITICAL:my_module:Running out of disk space.
</code></pre></div>

<div><h2 id="introspection"><a href="#introspection" name="introspection">#</a>Introspection</h2><pre><code class="python language-python hljs">&lt;list&gt; = dir() <span class="hljs-comment"># Names of local vars, functions, classes and modules.</span>
Expand Down Expand Up @@ -2932,7 +2932,7 @@ <h3 id="format-2">Format</h3><div><h4 id="forstandardtypesizesandmanualalignment


<footer>
<aside>August 18, 2024</aside>
<aside>August 19, 2024</aside>
<a href="https://gto76.github.io" rel="author">Jure Šorn</a>
</footer>

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