Created
January 1, 2019 01:31
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Taking ownership: copy versus move.
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| /* | |
| This program outputs: | |
| Bonjour 5 | |
| Hello 5 | |
| Bonjour 7 | |
| Bonjour 11 | |
| Hello 11 | |
| */ | |
| fn main() { | |
| // Scenario 1: taking ownership of a primitive type | |
| let bar = Bar{ value: 5 }; | |
| take_u32(bar.value); | |
| println!("Hello {}", bar.value); // legal: value was copied | |
| // Scenario 2: taking ownership of a struct instance | |
| let foo = Foo { | |
| bar: Bar { value: 7 } | |
| }; | |
| take_bar(foo.bar); | |
| // println!("Hello {}", foo.bar.value); // illegal: bar was moved | |
| // Scenario 3: taking ownership of a copyable struct instance | |
| let other_foo = OtherFoo { | |
| bar: CopyableBar { value: 11 } | |
| }; | |
| take_copyable_bar(other_foo.bar); | |
| println!("Hello {}", other_foo.bar.value); // legal: bar was copied | |
| } | |
| // the following functions take ownerships | |
| fn take_u32(number: u32) { | |
| println!("Bonjour {}", number); | |
| } | |
| fn take_bar(bar: Bar) { | |
| println!("Bonjour {}", bar.value); | |
| } | |
| fn take_copyable_bar(bar: CopyableBar) { | |
| println!("Bonjour {}", bar.value); | |
| } | |
| // the structs used for this example | |
| struct Bar { | |
| value: u32 | |
| } | |
| struct Foo { | |
| bar: Bar | |
| } | |
| #[derive(Copy, Clone)] | |
| struct CopyableBar { | |
| value: u32 | |
| } | |
| struct OtherFoo { | |
| bar: CopyableBar | |
| } |
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