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向 struct 添加方法

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向 struct 添加方法 是 CoddyKit 上的免费 Mojo Academy 课时。这是第 3 节课，共 4 节。你可以在下方免费阅读本课时的完整内容 — 然后在浏览器中使用内置代码编辑器和全天候 AI 导师进行实践。这是 Mojo Academy 学习路径的一部分，你的进度在网页和 CoddyKit 应用中同步。 Mojo Academy 课程共包含 4 节课。

本课时的部分内容尚未翻译，以英文显示。

Data Plus Behavior

So far your struct only holds data. A method is a function that lives inside the struct and gives your type behavior. 🚀

Methods Live Inside

You write a method by defining a function indented inside the struct, right alongside its fields and __init__.

struct Point:
    var x: Int
    var y: Int
    fn show(self):
        print(self.x, self.y)

self Comes First

A method's first parameter is self, the instance it was called on. Through self the method reads and uses the struct's own fields.

fn show(self):
    print(self.x)

Calling a Method

You call a method with dot syntax on an instance. Mojo passes that instance in as self automatically for you.

var p = Point(3, 4)
p.show()

Methods Can Return Values

Like any function, a method can return a result. Declare the return type after an arrow and hand back a value.

fn sum(self) -> Int:
    return self.x + self.y

Methods Take Arguments Too

After self, a method can accept more arguments, just like a normal function, to work with extra data the caller provides.

fn scaled(self, factor: Int) -> Int:
    return self.x * factor

Read-Only by Default

A plain self parameter is borrowed, so the method can read fields but not change them. This keeps your data safe.

Mutating with mut self

To let a method change the instance, mark the parameter mut self. Now assignments to self.x actually update the value.

fn move_right(mut self, step: Int):
    self.x += step

Methods Build on Each Other

One method can call another through self, so you compose small behaviors into larger ones without repeating code.

fn report(self):
    print(self.sum())

Encapsulation in Action

Keeping fields and the methods that use them in one struct is encapsulation. The type owns both its data and how that data behaves.

A Struct That Does Work

Here a Point both stores coordinates and reports their sum. Your type is now active, not just a passive data container.

struct Point:
    var x: Int
    var y: Int
    fn sum(self) -> Int:
        return self.x + self.y

Quick Check

Let us check what you know about methods.

Recap

You gave your struct methods that read and even mutate its fields. Next you will compare Mojo structs with Python classes. 🧩

常见问题解答

「向 struct 添加方法」课时是免费的吗？

是的 — 「向 struct 添加方法」的完整文本可在网页上免费阅读。要进行交互式练习（内置代码编辑器和全天候 AI 导师）并解锁 Mojo Academy 课程的其余内容，请升级到 CoddyKit PRO。 Mojo Academy 课程共包含 4 节课。

「向 struct 添加方法」这节课中我会学到什么？

为您的类型赋予行为你通过在浏览器中直接运行的动手代码来练习 Mojo Academy，全天候 AI 导师会在你学习这节课的过程中回答你的问题。

学习 Mojo Academy 需要有经验吗？

无需任何先前经验。CoddyKit 上的 Mojo Academy 课程适合初学者到高级学习者，你可以从这里开始或从头开始，按照自己的节奏学习。这是第 3 节课，共 4 节。

「向 struct 添加方法」课时需要多长时间？

大多数 CoddyKit 课程大约需要 5–10 分钟。每节课都很精短且互动，所以你能稳步进步，并在网页和应用中从离开的地方继续。

我能在这节 Mojo Academy 课中编写并运行代码吗？

能。每节 Mojo Academy 课都包含内置代码编辑器，你可以在浏览器中直接编写并运行真实代码，并获得即时 AI 反馈 — 无需本地设置。

此课程中的所有课时

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