copy
An explicit Copy trait for MoonBit values
copy
trait
moonbit
moon add totto2727/copy@0.2.0
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0.2.0
License
MIT
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Last updated
14 days ago
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263
README#totto2727/copy
An explicit copy trait for MoonBit values.
MoonBit does not move values when they are passed to a function, so this package is not a marker for Rust-style move semantics. Copy::copy instead creates an independent logical copy. Composite implementations recursively copy their contents, while immutable storage may be shared when it cannot expose mutation.
Copy has no blanket or default implementation. Every custom type must explicitly define how its independent logical copy is constructed so mutable fields and collections cannot be shared accidentally.
#Generic copying
Use a Copy bound when an operation must produce a logically independent value:
fn[T : Copy] duplicate(value : T) -> (T, T) {
(Copy::copy(value), Copy::copy(value))
}
test {
debug_inspect(duplicate(42), content="(42, 42)")
}The package implements Copy for primitive and immutable scalar values, Option, Result, Array, FixedArray, ReadOnlyArray, Map, and two- and three-element tuples. Composite implementations require their contained values to implement Copy; map keys must also implement Hash and Eq.
#Custom mutable values
Mutable types define their own copy policy:
struct Counter {
mut value : Int
}
impl Copy for Counter with fn copy(self) {
Counter::{ value: self.value }
}
test {
let source = Counter::{ value: 1 }
let copied = Copy::copy(source)
copied.value = 2
debug_inspect((source.value, copied.value), content="(1, 2)")
}MoonBit's trait syntax and generic trait bounds are documented in the official Method and Trait reference.
#Copy
pub(open) trait Copy {
fn copy(Self) -> Self
}Describes values that can produce an independent logical copy.
Implementations for composite values recursively copy their contents. An
implementation may share immutable internal storage when doing so cannot
expose mutation through the returned value.
impl Copy for FixedArray[T]
impl Copy for ReadOnlyArray[T]Source Files
An explicit Copy trait for MoonBit values
copytraitmoonbit
0.2.0
MIT
Updated 14 days ago
263 downloads