使用 owned 获取所有权

You have borrowed for reading and inout for editing. The third convention lets a function take over a value entirely. 📦

An owned argument transfers ownership into the function. The function now holds the value as its very own to use or store.

You write owned before the parameter name. Inside, the function has full control: it can mutate, store, or consume the value.

With owned, the value's lifetime moves into the function. When the function ends, it is responsible for destroying the value.

Use owned when a function needs to keep the value, like storing it in a struct or a collection, rather than just reading it briefly.

Since the function owns the value, it may freely change it. There is no caller to protect, because the value now belongs to the function.

By default Mojo gives an owned parameter a fresh copy, so the caller's original stays intact unless you ask to move it.

If you no longer need the original, you can hand the value over instead of copying it. That transfer is the topic of the next lesson.

Choosing owned tells readers this function will keep the value. The signature documents the data's journey at a glance.

Now you have all three: borrowed reads, inout mutates in place, and owned takes the value over. Each maps to a clear intent.

Ask who should be responsible for the value after the call. If the answer is the function, reach for owned.

Let us check what owned means for a function.

owned hands a value's ownership to the function, which can keep, change, or destroy it. Use it when the function must own the data. 🎯