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Mark Pilgrim
463 lines
12 KiB
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463 lines
12 KiB
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<!DOCTYPE html>
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<title>Special Method Names - Dive into Python 3</title>
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<form action=http://www.google.com/cse><div><input type=hidden name=cx value=014021643941856155761:l5eihuescdw><input type=hidden name=ie value=UTF-8> <input name=q size=25> <input type=submit name=sa value=Search></div></form>
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<p>You are here: <a href=index.html>Home</a> <span>‣</span> <a href=table-of-contents.html#special-method-names>Dive Into Python 3</a> <span>‣</span>
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<p id=level>Difficulty level: <span title=advanced>♦♦♦♦♦</span>
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<h1>Special Method Names</h1>
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<blockquote class=q>
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<p><span>❝</span> FIXME <span>❞</span><br>— FIXME
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</blockquote>
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<p id=toc>
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<h2 id=divingin>Diving in</h2>
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<p class=f>FIXME
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<h2 id=basics>Basics</h2>
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<pre>
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__init__ - covered in iterators.html
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__repr__ - covered in ordereddict.py
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__str__ - covered in fractions.py
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__bytes__ (*)
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__format__
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</pre>
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<h2 id=rich-comparisons>Rich Comparisons</h2>
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<pre>
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__lt__ - covered in fractions.py
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__le__ - covered in fractions.py
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__eq__ - covered in ordereddict.py, fractions.py
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__ne__
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__gt__ - covered in fractions.py
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__ge__ - covered in fractions.py
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__bool__ - covered in fractions.py
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__cmp__ (*)
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</pre>
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<h2 id=custom-attributes>Custom Attributes</h2>
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<pre>
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__getattr__
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__getattribute__
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__setattr__
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__delattr__
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__dir__
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</pre>
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<h2 id=acts-like-function>Classes That Act Like Functions</h2>
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<pre>
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__call__
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</pre>
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<h2 id=acts-like-list>Classes That Act Like Sequences</h2>
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<p>FIXME sequence intro
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<table>
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<tr><th>Notes
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<th>You Want…
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<th>So You Write…
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<th>And Python Calls…
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<tr><th>
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<td>length of a sequence
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<td><code>len(seq)</code>
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<td><code>seq.__len__()</code>
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<tr><th>
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<td>whether a sequence contains a specific value
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<td><code>x in seq</code>
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<td><code>seq.__contains__(<var>x</var>)</code>
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</table>
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<!--
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__len__
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__contains__
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-->
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<h2 id=acts-like-dict>Classes That Act Like Dictionaries</h2>
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<pre>
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__getitem__
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__setitem__ - covered in ordereddict.py
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__delitem__ - covered in ordereddict.py
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__missing__ (*)
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</pre>
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<h2 id=acts-like-iterator>Classes That Act Like Iterators</h2>
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<!--
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<tr><th>
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<td>reversed sequence
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<td><code>reversed(seq)</code>
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<td><code>x.__reversed__()</code>
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-->
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<pre>
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__iter__ (*) - covered in iterators.html
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__next__ (*) - covered in iterators.html
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__reversed__ - covered in ordereddict.py
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</pre>
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<h2 id=acts-like-number>Classes That Act Like Numbers</h2>
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<p>FIXME binary operator intro
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<table>
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<tr><th>Notes
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<th>You Want…
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<th>So You Write…
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<th>And Python Calls…
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<tr><th>
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<td>addition
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<td><code>x + y</code>
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<td><code>x.__add__(<var>y</var>)</code>
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<tr><th>
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<td>subtraction
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<td><code>x - y</code>
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<td><code>x.__sub__(<var>y</var>)</code>
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<tr><th>
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<td>multiplication
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<td><code>x * y</code>
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<td><code>x.__mul__(<var>y</var>)</code>
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<tr><th>
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<td>division
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<td><code>x / y</code>
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<td><code>x.__truediv__(<var>y</var>)</code>
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<tr><th>
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<td>floor division
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<td><code>x // y</code>
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<td><code>x.__floordiv__(<var>y</var>)</code>
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<tr><th>
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<td>modulo (remainder)
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<td><code>x % y</code>
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<td><code>x.__mod__(<var>y</var>)</code>
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<tr><th>
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<td>floor division <i class=baa>&</i> modulo
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<td><code>divmod(x, y)</code>
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<td><code>x.__divmod__(<var>y</var>)</code>
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<tr><th>
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<td>raise to power
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<td><code>x ** y</code>
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<td><code>x.__pow__(<var>y</var>)</code>
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<tr><th>
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<td>left bit-shift
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<td><code>x << y</code>
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<td><code>x.__lshift__(<var>y</var>)</code>
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<tr><th>
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<td>right bit-shift
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<td><code>x >> y</code>
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<td><code>x.__rshift__(<var>y</var>)</code>
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<tr><th>
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<td>bitwise <code>and</code>
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<td><code>x & y</code>
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<td><code>x.__and__(<var>y</var>)</code>
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<tr><th>
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<td>bitwise <code>xor</code>
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<td><code>x ^ y</code>
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<td><code>x.__xor__(<var>y</var>)</code>
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<tr><th>
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<td>bitwise <code>or</code>
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<td><code>x | y</code>
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<td><code>x.__or__(<var>y</var>)</code>
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</table>
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<!--
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__add__ - covered in fractions.py
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__sub__
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__mul__
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__truediv__
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__floordiv__ - covered in fractions.py
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__mod__ - covered in fractions.py
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__divmod__
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__pow__ - covered in fractions.py
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__lshift__
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__rshift__
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__and__
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__xor__
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__or__
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-->
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<p>FIXME explain circumstances under which reflected methods will be called. <!-- If <var>x</var> doesn't implement a given special method, or if it implements it but return <code>NotImplemented</code>, the Python interpreter will try a different approach — calling a special method on <var>y</var> instead of <var>x</var>.-->
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<table>
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<tr><th>Notes
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<th>You Want…
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<th>So You Write…
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<th>And Python Calls…
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<tr><th>
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<td>addition
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<td><code>x + y</code>
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<td><code>y.__radd__(<var>x</var>)</code>
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<tr><th>
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<td>subtraction
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<td><code>x - y</code>
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<td><code>y.__rsub__(<var>x</var>)</code>
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<tr><th>
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<td>multiplication
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<td><code>x * y</code>
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<td><code>y.__rmul__(<var>x</var>)</code>
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<tr><th>
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<td>division
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<td><code>x / y</code>
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<td><code>y.__rtruediv__(<var>x</var>)</code>
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<tr><th>
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<td>floor division
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<td><code>x // y</code>
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<td><code>y.__rfloordiv__(<var>x</var>)</code>
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<tr><th>
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<td>modulo (remainder)
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<td><code>x % y</code>
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<td><code>y.__rmod__(<var>x</var>)</code>
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<tr><th>
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<td>floor division <i class=baa>&</i> modulo
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<td><code>divmod(x, y)</code>
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<td><code>y.__rdivmod__(<var>x</var>)</code>
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<tr><th>
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<td>raise to power
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<td><code>x ** y</code>
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<td><code>y.__rpow__(<var>x</var>)</code>
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<tr><th>
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<td>left bit-shift
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<td><code>x << y</code>
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<td><code>y.__rlshift__(<var>x</var>)</code>
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<tr><th>
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<td>right bit-shift
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<td><code>x >> y</code>
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<td><code>y.__rrshift__(<var>x</var>)</code>
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<tr><th>
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<td>bitwise <code>and</code>
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<td><code>x & y</code>
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<td><code>y.__rand__(<var>x</var>)</code>
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<tr><th>
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<td>bitwise <code>xor</code>
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<td><code>x ^ y</code>
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<td><code>y.__rxor__(<var>x</var>)</code>
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<tr><th>
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<td>bitwise <code>or</code>
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<td><code>x | y</code>
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<td><code>y.__ror__(<var>x</var>)</code>
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</table>
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<!--
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__radd__ - covered in fractions.py
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__rsub__
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__rmul__
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__rtruediv__
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__rfloordiv__ - covered in fractions.py
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__rmod__ - covered in fractions.py
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__rpow__ - covered in fractions.py
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__rlshift__
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__rrshift__
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__rand__
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__rxor__
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__ror__
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-->
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<p>FIXME explain in-place augmented assignments
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<table>
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<tr><th>Notes
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<th>You Want…
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<th>So You Write…
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<th>And Python Calls…
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<tr><th>
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<td>in-place addition
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<td><code>x += y</code>
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<td><code>x.__iadd__(<var>y</var>)</code>
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<tr><th>
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<td>in-place subtraction
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<td><code>x -= y</code>
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<td><code>x.__isub__(<var>y</var>)</code>
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<tr><th>
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<td>in-place multiplication
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<td><code>x *= y</code>
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<td><code>x.__imul__(<var>y</var>)</code>
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<tr><th>
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<td>in-place division
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<td><code>x /= y</code>
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<td><code>x.__itruediv__(<var>y</var>)</code>
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<tr><th>
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<td>in-place floor division
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<td><code>x //= y</code>
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<td><code>x.__ifloordiv__(<var>y</var>)</code>
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<tr><th>
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<td>in-place modulo
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<td><code>x %= y</code>
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<td><code>x.__imod__(<var>y</var>)</code>
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<tr><th>
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<td>in-place raise to power
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<td><code>x **= y</code>
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<td><code>x.__ipow__(<var>y</var>)</code>
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<tr><th>
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<td>in-place left bit-shift
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<td><code>x <<= y</code>
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<td><code>x.__ilshift__(<var>y</var>)</code>
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<tr><th>
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<td>in-place right bit-shift
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<td><code>x >>= y</code>
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<td><code>x.__irshift__(<var>y</var>)</code>
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<tr><th>
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<td>in-place bitwise <code>and</code>
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<td><code>x &= y</code>
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<td><code>x.__iand__(<var>y</var>)</code>
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<tr><th>
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<td>in-place bitwise <code>xor</code>
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<td><code>x ^= y</code>
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<td><code>x.__ixor__(<var>y</var>)</code>
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<tr><th>
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<td>in-place bitwise <code>or</code>
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<td><code>x |= y</code>
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<td><code>x.__ior__(<var>y</var>)</code>
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</table>
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<!--
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__iadd__
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__isub__
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__imul__
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__itruediv__
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__ifloordiv__
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__imod__
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__ipow__
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__ilshift__
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__irshift__
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__iand__
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__ixor__
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__ior__
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-->
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<p>FIXME unary operator intro
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<table>
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<tr><th>Notes
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<th>You Want…
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<th>So You Write…
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<th>And Python Calls…
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<tr><th>
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<td>negative number
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<td><code>-x</code>
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<td><code>x.__neg__()</code>
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<tr><th>
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<td>positive number
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<td><code>+x</code>
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<td><code>x.__pos__()</code>
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<tr><th>
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<td>absolute value
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<td><code>abs(x)</code>
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<td><code>x.__abs__()</code>
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<tr><th>
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<td>inverse
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<td><code>~x</code>
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<td><code>x.__invert__()</code>
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<tr><th>
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<td>complex number
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<td><code>complex(x)</code>
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<td><code>x.__complex__()</code>
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<tr><th>
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<td>integer
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<td><code>int(x)</code>
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<td><code>x.__int__()</code>
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<tr><th>
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<td>floating point number
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<td><code>float(x)</code>
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<td><code>x.__float__()</code>
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<tr><th>
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<td>number rounded to nearest integer
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<td><code>round(x)</code>
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<td><code>x.__round__()</code>
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<tr><th>
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<td>number rounded to nearest <var>n</var> digits
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<td><code>round(x, n)</code>
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<td><code>x.__round__(n)</code>
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<tr><th>
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<td>smallest integer <code>>= x</code>
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<td><code>math.ceil(x)</code>
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<td><code>x.__ceil__()</code>
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<tr><th>
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<td>largest integer <code><= x</code>
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<td><code>math.floor(x)</code>
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<td><code>x.__floor__()</code>
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<tr><th>
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<td>truncate <code>x</code> to nearest integer toward <code>0</code>
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<td><code>math.trunc(x)</code>
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<td><code>x.__trunc__()</code>
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<tr><th>
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<td>???
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<td><code>???</code>
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<td><code>x.__index__()</code>
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</table>
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<!--
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__neg__ - covered in fractions.py
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__pos__ - covered in fractions.py
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__abs__ - covered in fractions.py
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__invert__
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__complex__
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__int__
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__float__
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__round__ - covered in fractions.py
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__ceil__ (*) - covered in fractions.py
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__floor__ (*) - covered in fractions.py
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__trunc__ (*) - covered in fractions.py
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__index__
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-->
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<h2 id=pickle>Support For Pickling</h2>
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<pre>
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see http://docs.python.org/3.0/library/pickle.html:
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__copy__ (*) - covered in fractions.py
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__deepcopy__ (*) - covered in fractions.py
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__getnewargs__ (*)
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__getinitargs__ (*)
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__getstate__ (*)
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__setstate__ (*)
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__reduce__ (*) - covered in ordereddict.py, fractions.py
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__reduce_ex__ (*)
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</pre>
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<h2 id=context-managers>Classes That Can Be Used in a <code>with</code> Block</h2>
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<pre>
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__enter__ see http://docs.python.org/3.0/library/stdtypes.html#typecontextmanager
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__exit__
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</pre>
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<h2 id=esoterica>Really Esoteric Stuff</h2>
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<pre>
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__new__ - covered in fractions.py
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__del__
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__slots__
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__hash__ - covered in fractions.py
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__get__
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__set__
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__delete__
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__subclasshook__ (*) see http://docs.python.org/3.0/library/abc.html
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__instancecheck__ (*) see http://www.ibm.com/developerworks/linux/library/l-python3-2/
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__subclasscheck__ (*)
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</pre>
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<p class=nav><a rel=prev href=porting-code-to-python-3-with-2to3.html title="back to “Porting code to Python 3 with 2to3”"><span>☜</span></a> <a rel=next class=todo><span>☞</span></a>
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<p class=c>© 2001–9 <a href=about.html>Mark Pilgrim</a>
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<script src=jquery.js></script>
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<script src=dip3.js></script>
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