<p>Python的魔法方法通過(guò)定義特殊方法使對(duì)象支持內(nèi)置操作。它們?cè)试S類(lèi)實(shí)例使用標(biāo)準(zhǔn)語(yǔ)法進(jìn)行交互，如運(yùn)算符或print函數(shù)。 __str__用於用戶(hù)友好顯示，__repr__用於調(diào)試信息。 __add__等方法可重載運(yùn)算符行為，實(shí)現(xiàn)對(duì)象相加、比較等功能。 __call__方法讓對(duì)象可調(diào)用，適用於需維持狀態(tài)的場(chǎng)景。常見(jiàn)方法包括：1.__str__和__repr__控制輸出格式；2.__add__、__sub__等實(shí)現(xiàn)運(yùn)算符重載；3.__call__使對(duì)象具備函數(shù)行為。這些方法增強(qiáng)自定義類(lèi)型與Python語(yǔ)言特性的集成度，減少冗餘代碼。 </p> <p><img src="/static/imghw/default1.png" data-src="https://img.php.cn/upload/article/000/000/000/174902311294753.jpg" class="lazy" alt="What are Python\'s \" magic or methods __str__ __repr__ __add__ and how do they enable operator overloading></p> <p> Python's magic methods (also called dunder methods, short for "double underscore") are special methods that let you define behaviors for built-in operations. These methods allow objects of your classes to interact with standard Python syntax in a natural way — like using<code> </code>for addition or <code>print()</code> for displaying values.</p> <p> Here's how some common ones work and what they're used for.</p> <hr> <h3 id="code-str-code-vs-code-repr-code-Controlling-How-Objects-Are-Displayed"> <code>__str__</code> vs. <code>__repr__</code> : Controlling How Objects Are Displayed</h3> <p> When you print an object or convert it to a string, Python looks for the <code>__str__</code> method. If that's not defined, it falls back to <code>__repr__</code> .</p> <ul> <li> <code>__str__</code> is meant to be user-friendly.</li> <li> <code>__repr__</code> is meant to be unambiguous and useful for debugging.</li> </ul> <p> For example:</p><pre class='brush:php;toolbar:false;'> class Book: def __init__(self, title, author): self.title = title self.author = author def __repr__(self): return f"Book(title=&#39;{self.title}&#39;, author=&#39;{self.author}&#39;)" def __str__(self): return f"{self.title} by {self.author}"</pre><p> Now if you create a <code>Book</code> instance:</p><pre class='brush:php;toolbar:false;'> b = Book("1984", "George Orwell") print(b) # Uses __str__: "1984 by George Orwell" print(repr(b)) # Explicitly uses __repr__: "Book(title=&#39;1984&#39;, author=&#39;George Orwell&#39;)"</pre><p> Use <code>__str__</code> when you want a nice output for users, and <code>__repr__</code> when you want something helpful during development.</p><hr /><h3 id="code-add-code-and-Other-Operators-Overloading-How-Objects-Interact"> <code>__add__</code> and Other Operators: Overloading How Objects Interact</h3><p> Python lets you define what happens when you use operators like<code> </code>, <code>-</code> , <code>*</code> , etc., with your objects. This is called <strong>operator overloading</strong> .</p><p> The <code>__add__</code> method defines behavior for the<code> </code>operator. For example:</p><pre class='brush:php;toolbar:false;'> class Point: def __init__(self, x, y): self.x = x self.y = y def __add__(self, other): return Point(self.x other.x, self.y other.y)</pre><p> Now you can do this:</p><pre class='brush:php;toolbar:false;'> p1 = Point(1, 2) p2 = Point(3, 4) p3 = p1 p2 # Returns a new Point with x=4 and y=6</pre><p> Some other common operator methods include:</p><ul><li> <code>__sub__</code> for <code>-</code></li><li> <code>__mul__</code> for <code>*</code></li><li> <code>__truediv__</code> for <code>/</code></li><li> <code>__eq__</code> for <code>==</code></li><li> <code>__lt__</code> for <code><</code></li></ul><p> Each one gives you control over how your custom types behave in expressions.</p><hr /><h3 id="Making-Objects-Callable-with-code-call-code"> Making Objects Callable with <code>__call__</code></h3><p> If you want an instance of your class to be callable — like a function — implement the <code>__call__</code> method.</p><p> This can be handy for maintaining state between calls:</p><pre class='brush:php;toolbar:false;'> class Counter: def __init__(self): self.count = 0 def __call__(self): self.count = 1 return self.count</pre><p> Usage:</p><pre class='brush:php;toolbar:false;'> counter = Counter() print(counter()) # 1 print(counter()) # 2</pre><p> It's a neat trick when you want something function-like but with memory.</p> <hr> <p> These are just a few of the many dunder methods available in Python. They give you powerful tools to make your classes feel more integrated with the language itself.</p> <p> You don't need to use all of them right away, but knowing how to reach for the right one at the right time can save you from writing unnecessary boilerplate code.</p> <p> Basically, that's how magic methods work — they hook into Python's built-in behaviors so your objects can play nicely with the rest of the language.</p> <p> And yeah, it's not magic after all — just good design.</p>

以上是Python的'魔術(shù)”或' dunder”方法是什麼（例如__Str__，__repr__，__ADD__），它們?nèi)绾问共僮鲉T超負(fù)荷？的詳細(xì)內(nèi)容。更多資訊請(qǐng)關(guān)注PHP中文網(wǎng)其他相關(guān)文章！