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参数化 Struct

构建泛型且类型安全的容器

参数化 Struct 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。

Structs Take Parameters Too

A parameterized struct takes compile-time values in brackets, letting one definition become many type-safe, specialized containers. 📦

struct Box[T: AnyType]:
    var value: T

A Type Parameter

The T here is a type parameter. It stands in for whatever type you fill in when you actually create the struct.

Naming the Concrete Type

When you use the struct, you supply the type in brackets, turning the generic blueprint into a concrete, fixed type.

var b = Box[Int](42)

Many Types, One Blueprint

The same blueprint gives you Box[Int], Box[Float64], and more, each a distinct type the compiler tailors for you.

var f = Box[Float64](3.14)

Numeric Parameters

Parameters need not be types. A numeric parameter can fix a size, like the length of a fixed-capacity array.

struct Buffer[size: Int]:
    var count: Int

Size Known Up Front

With size as a parameter, the compiler knows the exact layout in advance and can lay out memory with zero runtime guesswork.

Methods See the Parameters

Inside the struct, every method can use the parameters freely, so behavior adapts to the type or size you chose.

struct Pair[T: AnyType]:
    var a: T
    var b: T

Type Safety for Free

A Box[Int] simply will not accept a Float. The compiler enforces the parameter, catching mix-ups before the program ever runs.

Multiple Parameters

A struct can list several parameters at once, combining types and sizes to describe exactly the container you need.

struct Grid[T: AnyType, rows: Int, cols: Int]:
    var total: Int

How SIMD Uses This

The built-in SIMD type is itself a parameterized struct: its element type and width are both compile-time parameters.

var v = SIMD[DType.float32, 4](1, 2, 3, 4)

Generic and Fast

Parameterized structs give you Python-like generics with none of the overhead, since each version is specialized at compile time.

Quick Check

Recall what a parameterized struct can hold in its brackets.

Recap

You built parameterized structs: brackets hold types or sizes, one blueprint yields many specialized types, all checked and optimized at compile time. 🎯

常见问题解答

「参数化 Struct」课时是免费的吗？

是的 — 「参数化 Struct」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。

「参数化 Struct」这节课中我会学到什么？

构建泛型且类型安全的容器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。

「参数化 Struct」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。

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