เมธอด __moveinit__

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

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

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

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

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.

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

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

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

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

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

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

Lets check the move initializer.

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