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‎README.md

Lines changed: 21 additions & 8 deletions
Original file line numberDiff line numberDiff line change
@@ -929,21 +929,22 @@ class <name>:
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* **Return value of repr() should be unambiguous and of str() readable.**
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* **If only repr() is defined, it will also be used for str().**
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#### Str() is used by:
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#### Str() use cases:
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```python
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print(<el>)
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f'{<el>}'
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print(f'{<el>}')
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raise Exception(<el>)
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logging.debug(<el>)
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csv.writer(<file>).writerow([<el>])
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```
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#### Repr() is used by:
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#### Repr() use cases:
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```python
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print([<el>])
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f'{<el>!r}'
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print(f'{<el>!r}')
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>>> <el>
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loguru.logger.exception()
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Z = dataclasses.make_dataclass('Z', ['a']); print(Z(<el>))
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```
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### Constructor Overloading
@@ -1502,12 +1503,14 @@ def write_to_pickle_file(filename, an_object):
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SQLite
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------
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**Server-less database engine that stores each database into separate file.**
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```python
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import sqlite3
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db = sqlite3.connect('<path>') # Also ':memory:'.
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...
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db.close()
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```
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* **New database will be created if path doesn't exist.**
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### Read
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```python
@@ -1516,7 +1519,7 @@ if cursor:
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<tuple> = cursor.fetchone() # First row.
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<list> = cursor.fetchall() # Remaining rows.
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```
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* **Returned values can be of type str, int, float or bytes.**
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* **Returned values can be of type str, int, float, bytes or None.**
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### Write
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```python
@@ -1526,10 +1529,20 @@ db.commit()
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### Placeholders
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```python
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db.execute('<query>', <list/tuple>) # Replaces '?' in query with value.
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db.execute('<query>', <dict/namedtuple>) # Replaces ':<key>' with value.
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db.execute('<query>', <list/tuple>) # Replaces '?'s in query with values.
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db.execute('<query>', <dict/namedtuple>) # Replaces ':<key>'s with values.
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db.executemany('<query>', <coll_of_above>) # Runs execute() many times.
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```
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* **Passed values can be of type str, int, float, bytes, None, bool, datetime.date or datetime.datetme.**
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### MySQL
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```python
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# $ pip3 install mysql-connector
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from mysql import connector
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db = connector.connect(host=<str>, user=<str>, password=<str>, database=<str>)
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cursor = db.cursor()
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cursor.execute('<query>')
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```
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* **Passed values can be of type str, int, float, bytes, bool, datetime.date and datetime.datetme.**
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‎index.html

Lines changed: 21 additions & 8 deletions
Original file line numberDiff line numberDiff line change
@@ -883,18 +883,19 @@ <h2 id="class"><a href="#class" name="class">#</a>Class</h2>
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<li><strong>Return value of repr() should be unambiguous and of str() readable.</strong></li>
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<li><strong>If only repr() is defined, it will also be used for str().</strong></li>
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</ul>
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<h4 id="strisusedby">Str() is used by:</h4>
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<h4 id="strusecases">Str() use cases:</h4>
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<pre><code class="python language-python hljs">print(&lt;el&gt;)
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<span class="hljs-string">f'<span class="hljs-subst">{&lt;el&gt;}</span>'</span>
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print(<span class="hljs-string">f'<span class="hljs-subst">{&lt;el&gt;}</span>'</span>)
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<span class="hljs-keyword">raise</span> Exception(&lt;el&gt;)
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logging.debug(&lt;el&gt;)
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csv.writer(&lt;file&gt;).writerow([&lt;el&gt;])
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</code></pre>
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<h4 id="reprisusedby">Repr() is used by:</h4>
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<h4 id="reprusecases">Repr() use cases:</h4>
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<pre><code class="python language-python hljs">print([&lt;el&gt;])
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<span class="hljs-string">f'<span class="hljs-subst">{&lt;el&gt;!r}</span>'</span>
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print(<span class="hljs-string">f'<span class="hljs-subst">{&lt;el&gt;!r}</span>'</span>)
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<span class="hljs-meta">&gt;&gt;&gt; </span>&lt;el&gt;
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loguru.logger.exception()
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Z = dataclasses.make_dataclass(<span class="hljs-string">'Z'</span>, [<span class="hljs-string">'a'</span>]); print(Z(&lt;el&gt;))
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</code></pre>
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<h3 id="constructoroverloading">Constructor Overloading</h3>
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<pre><code class="python language-python hljs"><span class="hljs-class"><span class="hljs-keyword">class</span> &lt;<span class="hljs-title">name</span>&gt;:</span>
@@ -1323,31 +1324,43 @@ <h3 id="writeobjecttofile">Write Object to File</h3>
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pickle.dump(an_object, file)
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</code></pre>
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<h2 id="sqlite"><a href="#sqlite" name="sqlite">#</a>SQLite</h2>
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<p><strong>Server-less database engine that stores each database into separate file.</strong></p>
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<pre><code class="python language-python hljs"><span class="hljs-keyword">import</span> sqlite3
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db = sqlite3.connect(<span class="hljs-string">'&lt;path&gt;'</span>) <span class="hljs-comment"># Also ':memory:'.</span>
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...
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db.close()
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</code></pre>
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<ul>
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<li><strong>New database will be created if path doesn't exist.</strong></li>
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</ul>
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<h3 id="read">Read</h3>
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<pre><code class="python language-python hljs">cursor = db.execute(<span class="hljs-string">'&lt;query&gt;'</span>)
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<span class="hljs-keyword">if</span> cursor:
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&lt;tuple&gt; = cursor.fetchone() <span class="hljs-comment"># First row.</span>
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&lt;list&gt; = cursor.fetchall() <span class="hljs-comment"># Remaining rows.</span>
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</code></pre>
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<ul>
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<li><strong>Returned values can be of type str, int, float or bytes.</strong></li>
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<li><strong>Returned values can be of type str, int, float, bytes or None.</strong></li>
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</ul>
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<h3 id="write">Write</h3>
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<pre><code class="python language-python hljs">db.execute(<span class="hljs-string">'&lt;query&gt;'</span>)
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db.commit()
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</code></pre>
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<h3 id="placeholders">Placeholders</h3>
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<pre><code class="python language-python hljs">db.execute(<span class="hljs-string">'&lt;query&gt;'</span>, &lt;list/tuple&gt;) <span class="hljs-comment"># Replaces '?' in query with value.</span>
1346-
db.execute(<span class="hljs-string">'&lt;query&gt;'</span>, &lt;dict/namedtuple&gt;) <span class="hljs-comment"># Replaces ':&lt;key&gt;' with value.</span>
1350+
<pre><code class="python language-python hljs">db.execute(<span class="hljs-string">'&lt;query&gt;'</span>, &lt;list/tuple&gt;) <span class="hljs-comment"># Replaces '?'s in query with values.</span>
1351+
db.execute(<span class="hljs-string">'&lt;query&gt;'</span>, &lt;dict/namedtuple&gt;) <span class="hljs-comment"># Replaces ':&lt;key&gt;'s with values.</span>
1352+
db.executemany(<span class="hljs-string">'&lt;query&gt;'</span>, &lt;coll_of_above&gt;) <span class="hljs-comment"># Runs execute() many times.</span>
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</code></pre>
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<ul>
1349-
<li><strong>Passed values can be of type str, int, float, bytes, bool, datetime.date and datetime.datetme.</strong></li>
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<li><strong>Passed values can be of type str, int, float, bytes, None, bool, datetime.date or datetime.datetme.</strong></li>
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</ul>
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<h3 id="mysql">MySQL</h3>
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<pre><code class="python language-python hljs"><span class="hljs-comment"># $ pip3 install mysql-connector</span>
1359+
<span class="hljs-keyword">from</span> mysql <span class="hljs-keyword">import</span> connector
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db = connector.connect(host=&lt;str&gt;, user=&lt;str&gt;, password=&lt;str&gt;, database=&lt;str&gt;)
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cursor = db.cursor()
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cursor.execute(<span class="hljs-string">'&lt;query&gt;'</span>)
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</code></pre>
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<h2 id="bytes"><a href="#bytes" name="bytes">#</a>Bytes</h2>
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<p><strong>Bytes object is an immutable sequence of single bytes. Mutable version is called 'bytearray'.</strong></p>
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<pre><code class="python language-python hljs">&lt;bytes&gt; = <span class="hljs-string">b'&lt;str&gt;'</span> <span class="hljs-comment"># Only accepts ASCII characters and \x00 - \xff.</span>

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