Mojo Academy · 강의

moveinit 메서드

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__moveinit__ 메서드은(는) CoddyKit의 무료 Mojo Academy 강의입니다. 이것은 4개 중 3번째 강의입니다. 아래에서 전체 강의를 무료로 읽을 수 있으며, 내장 코드 에디터와 24/7 AI 튜터와 함께 브라우저에서 직접 실습할 수 있습니다. 이 강의는 Mojo Academy 학습 경로의 일부이며, 진행 상황이 웹과 CoddyKit 앱에 동기화됩니다. Mojo Academy 강의에는 총 4개의 강의가 포함되어 있습니다.

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Defining How to Move

To move a value, Mojo calls a special method named __moveinit__. It builds a new instance by taking over an old one. 🚚

It Runs on Transfer

When you use the caret transfer operator, __moveinit__ fires. It relocates the value instead of duplicating its data.

var b = a^   # calls __moveinit__

The Method Signature

It receives the new instance and the owned source value. Because the source is owned, you may consume it directly.

fn __moveinit__(out self, owned existing: Self):
    self.ptr = existing.ptr

Steal, Do Not Copy

The trick is to transfer resources like a heap pointer from the source to the new instance, rather than allocating again.

No Double Free

After the move, the source must not free the data it gave away. Mojo handles this so the buffer is owned by exactly one instance.

Cheap for Big Values

Because __moveinit__ shuffles ownership instead of cloning bytes, moving a huge buffer costs almost nothing. That is the speed win.

Source Becomes Invalid

Once moved from, the source is consumed. Mojo stops you from reading it, guaranteeing you never touch relocated data.

Often Derived for You

Like copying, you usually do not write this. Conforming to Movable lets Mojo synthesize a field-wise __moveinit__ for you.

When to Write It Yourself

Customize __moveinit__ when your type owns a resource that needs explicit hand-off, such as a manually managed pointer.

Pairs with Copy

A type can define both copy and move. Mojo then picks the cheaper one, choosing a move whenever the source is no longer needed.

Enables Cheap Ownership

__moveinit__ is what makes ownership transfer fast and safe. It lets values flow through your program without wasteful duplication.

Quick Check

Lets check the move initializer.

Recap

__moveinit__ defines how your type moves, handing resources to a new instance cheaply and consuming the source. 🎯

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