Transfer operator inside constructor and moveinit

I have a question regarding using the transfer operator inside constructor and moveinit as shown in this example:

https://docs.modular.com/mojo/manual/lifecycle/life#move-constructor

struct MyPet:
    var name: String
    var age: Int

    fn __init__(inout self, owned name: String, age: Int):
        self.name = name^
        self.age = age

    fn __copyinit__(inout self, existing: Self):
        self.name = existing.name
        self.age = existing.age

    fn __moveinit__(inout self, owned existing: Self):
        self.name = existing.name^
        self.age = existing.age

fn example_movable(owned pet: Pet):
  print(pet.name)

struct MyPet:
    var name: String
    var age: Int

    fn __init__(inout self, owned name: String, age: Int):
        self.name = name^
        self.age = age

    fn __copyinit__(inout self, existing: Self):
        self.name = existing.name
        self.age = existing.age

    fn __moveinit__(inout self, owned existing: Self):
        self.name = existing.name^
        self.age = existing.age

fn example_movable(owned pet: Pet):
  print(pet.name)

This confuses me a little as I thought that the transfer operator was to be used only while calling the function or assignment something like this:

var foo = MyPet("a", 10)
var bar = foo^ # this works as expected

example_movable(bar^)

var foo = MyPet("a", 10)
var bar = foo^ # this works as expected

example_movable(bar^)

Now, what does it mean for the dunder methods to use ^ operator for assignment? Does it mean the same thing as mentioned above? I tried asking the bot for help as well, but it seems to think that this is an incorrect way of doing.

https://discord.com/channels/1087530497313357884/1228421383206473869/1228426919851327578

Life of a value | Modular Docs

An explanation of when and how Mojo creates values.

Modular•2y ago•

10 replies

Grandimam

Transfer operator inside constructor and moveinit

I have a question regarding using the transfer operator inside constructor and moveinit as shown in this example:

https://docs.modular.com/mojo/manual/lifecycle/life#move-constructor

struct MyPet:
    var name: String
    var age: Int

    fn __init__(inout self, owned name: String, age: Int):
        self.name = name^
        self.age = age

    fn __copyinit__(inout self, existing: Self):
        self.name = existing.name
        self.age = existing.age

    fn __moveinit__(inout self, owned existing: Self):
        self.name = existing.name^
        self.age = existing.age

fn example_movable(owned pet: Pet):
  print(pet.name)

struct MyPet:
    var name: String
    var age: Int

    fn __init__(inout self, owned name: String, age: Int):
        self.name = name^
        self.age = age

    fn __copyinit__(inout self, existing: Self):
        self.name = existing.name
        self.age = existing.age

    fn __moveinit__(inout self, owned existing: Self):
        self.name = existing.name^
        self.age = existing.age

fn example_movable(owned pet: Pet):
  print(pet.name)

This confuses me a little as I thought that the transfer operator was to be used only while calling the function or assignment something like this:

var foo = MyPet("a", 10)
var bar = foo^ # this works as expected

example_movable(bar^)

var foo = MyPet("a", 10)
var bar = foo^ # this works as expected

example_movable(bar^)

Life of a value | Modular Docs

An explanation of when and how Mojo creates values.

Transfer operator inside constructor and moveinit

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Transfer operator inside constructor and moveinit

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