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The Copyable trait denotes a type whose value can be copied.

Example implementing the Copyable trait on Foo which requires the __copyinit__ method:

struct Foo(Copyable):
var s: String

fn __init__(inout self, s: String):
self.s = s

fn __copyinit__(inout self, other: Self):
print("copying value")
self.s = other.s

You can now copy objects inside a generic function:

fn copy_return[T: Copyable](foo: T) -> T:
var copy = foo
return copy

var foo = Foo("test")
var res = copy_return(foo)
copying value

Implemented traits




__copyinit__(inout self: T, existing: T, /)

Create a new instance of the value by copying an existing one.


  • existing (T): The value to copy.