Trait objc2::encode::Encode

source ·

pub unsafe trait Encode {
    const ENCODING: Encoding;
}

Expand description

Types that have an Objective-C type-encoding.

Usually you will want to implement RefEncode as well.

If your type is an opaque type you should not need to implement this; there you will only need RefEncode.

§Safety

The type must be FFI-safe, meaning a C-compatible repr (repr(C), repr(u8), repr(transparent) where the inner types are C-compatible, and so on). See the nomicon on other reprs.

Objective-C will make assumptions about the type (like its size, alignment and ABI) from its encoding, so the implementer must verify that the encoding is accurate.

Concretely, Self::ENCODING must match the result of running @encode in Objective-C with the type in question.

You should also beware of having Drop types implement this, since when passed to Objective-C via. objc2::msg_send! their destructor will not be called!

§Examples

Implementing for a struct:

#[repr(C)]
struct MyType {
    a: i32,
    b: f64,
    c: *const c_void,
}

unsafe impl Encode for MyType {
    const ENCODING: Encoding = Encoding::Struct(
        // The name of the type that Objective-C sees.
        "MyType",
        &[
            // Delegate to field's implementations.
            // The order is the same as in the definition.
            i32::ENCODING,
            f64::ENCODING,
            <*const c_void>::ENCODING,
        ],
    );
}

// Note: You would also implement `RefEncode` for this type.

Required Associated Constants§

source

const ENCODING: Encoding

The Objective-C type-encoding for this type.

Object Safety§

This trait is not object safe.

Trait objc2::encode::EncodeCopy item path

§Safety

§Examples

Required Associated Constants§

const ENCODING: Encoding

Object Safety§

Implementations on Foreign Types§

impl Encode for f32

const ENCODING: Encoding = Encoding::Float

impl Encode for f64

const ENCODING: Encoding = Encoding::Double

impl Encode for i8

const ENCODING: Encoding = Encoding::Char

impl Encode for i16

const ENCODING: Encoding = Encoding::Short

impl Encode for i32

const ENCODING: Encoding = Encoding::Int

impl Encode for i64

const ENCODING: Encoding = Encoding::LongLong

impl Encode for isize

const ENCODING: Encoding = i64::ENCODING

impl Encode for u8

const ENCODING: Encoding = Encoding::UChar

impl Encode for u16

const ENCODING: Encoding = Encoding::UShort

impl Encode for u32

const ENCODING: Encoding = Encoding::UInt

impl Encode for u64

const ENCODING: Encoding = Encoding::ULongLong

impl Encode for usize

const ENCODING: Encoding = u64::ENCODING

impl Encode for AtomicI8

const ENCODING: Encoding = _

impl Encode for AtomicI16

const ENCODING: Encoding = _

impl Encode for AtomicI32

const ENCODING: Encoding = _

impl Encode for AtomicI64

const ENCODING: Encoding = _

impl Encode for AtomicIsize

const ENCODING: Encoding = _

impl Encode for AtomicU8

const ENCODING: Encoding = _

impl Encode for AtomicU16

const ENCODING: Encoding = _

impl Encode for AtomicU32

const ENCODING: Encoding = _

impl Encode for AtomicU64

const ENCODING: Encoding = _

impl Encode for AtomicUsize

const ENCODING: Encoding = _

impl Encode for NonZeroI8

const ENCODING: Encoding = i8::ENCODING

impl Encode for NonZeroI16

const ENCODING: Encoding = i16::ENCODING

impl Encode for NonZeroI32

const ENCODING: Encoding = i32::ENCODING

impl Encode for NonZeroI64

const ENCODING: Encoding = i64::ENCODING

impl Encode for NonZeroIsize

const ENCODING: Encoding = isize::ENCODING

impl Encode for NonZeroU8

const ENCODING: Encoding = u8::ENCODING

impl Encode for NonZeroU16

const ENCODING: Encoding = u16::ENCODING

impl Encode for NonZeroU32

const ENCODING: Encoding = u32::ENCODING

impl Encode for NonZeroU64

const ENCODING: Encoding = u64::ENCODING

impl Encode for NonZeroUsize

const ENCODING: Encoding = usize::ENCODING

impl<'a, T: RefEncode + ?Sized> Encode for &'a T

const ENCODING: Encoding = T::ENCODING_REF

impl<'a, T: RefEncode + ?Sized> Encode for &'a mut T

const ENCODING: Encoding = T::ENCODING_REF

impl<Ret: EncodeReturn> Encode for extern "C" fn() -> Ret

const ENCODING: Encoding = _

impl<Ret: EncodeReturn> Encode for unsafe extern "C" fn() -> Ret

const ENCODING: Encoding = _

impl<Ret: EncodeReturn, A: EncodeArgument> Encode for extern "C" fn(_: A) -> Ret

Trait objc2::encode::Encode