pub struct Enum<T: Copy + Into<u8> + TryFrom<u8>>(_);
Expand description

The implementation of the pass by enum strategy. This strategy uses an u8 internally to pass the enum between wasm and the host. So, this strategy only supports enums with unit variants.

Use this type as associated type for PassBy to implement this strategy for a type.

This type expects the type that wants to implement this strategy as generic parameter. Besides that the type needs to implement TryFrom<u8> and From<Self> for u8.

PassByEnum is a derive macro to implement this strategy.

Example

#[derive(Clone, Copy)]
enum Test {
    Test1,
    Test2,
}

impl From<Test> for u8 {
    fn from(val: Test) -> u8 {
        match val {
            Test::Test1 => 0,
            Test::Test2 => 1,
        }
    }
}

impl std::convert::TryFrom<u8> for Test {
    type Error = ();

    fn try_from(val: u8) -> Result<Test, ()> {
        match val {
            0 => Ok(Test::Test1),
            1 => Ok(Test::Test2),
            _ => Err(()),
        }
    }
}

impl PassBy for Test {
    type PassBy = Enum<Self>;
}

Trait Implementations

Convert the given instance to the ffi value. Read more

Create T from the given ffi value. Read more

The type is passed as u8.

The value is corresponds to the discriminant of the variant.

The ffi type that is used to represent Self.

Auto Trait Implementations

Blanket Implementations

Gets the TypeId of self. Read more

Immutably borrows from an owned value. Read more

Mutably borrows from an owned value. Read more

Returns the argument unchanged.

Instruments this type with the provided Span, returning an Instrumented wrapper. Read more

Instruments this type with the current Span, returning an Instrumented wrapper. Read more

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

The type returned in the event of a conversion error.

Performs the conversion.

The type returned in the event of a conversion error.

Performs the conversion.