Trait StoredValue 

pub trait StoredValue:
    Clone
    + Send
    + 'static {
    // Required methods
    fn metadata() -> *const c_void;
    fn field_type() -> &'static [u8] ;
    fn mangled() -> &'static str;
    fn buffer_bytes() -> usize;
    unsafe fn init_storage(&self, key: &str) -> u64;
    unsafe fn decode(buf: &[u8]) -> Self;
    fn encode(&self) -> Vec<u8> ;
}

A type @AppStorage can hold.

The four AppStorage takes without a RawRepresentable detour. The accessors are generic over Value and so are shared — only the initialiser differs per type, and it differs in ways worth having read rather than guessed. From swiftc -emit-ir:

  AppStorage<Bool>.init   (i1,     i64, ptr, i64)        ; x0=value, x1/x2=key, x3=store
  AppStorage<Int>.init    (i64,    i64, ptr, i64)        ; x0=value, x1/x2=key, x3=store
  AppStorage<Double>.init (double, i64, ptr, i64)        ; d0=value, x0/x1=key, x2=store
  AppStorage<String>.init (i64, ptr, i64, ptr, i64)      ; x0/x1=value, x2/x3=key, x4=store

Double is the one that breaks the pattern: its value travels in a float register, so the key and the store shift down one.

Required Methods

fn metadata() -> *const c_void

Value.Type — what the accessors want in x1, not AppStorage<Value>’s.

fn field_type() -> &'static [u8]

The mangled AppStorage<Self>, NUL-terminated, for the field record.

fn mangled() -> &'static str

Self’s own mangling, for naming Binding<Self>.

fn buffer_bytes() -> usize

How many bytes the accessors read and write.

unsafe fn init_storage(&self, key: &str) -> u64

Build the wrapper, returning its UserDefaultLocation.

Safety

Calls into SwiftUI; key must be a valid string.

unsafe fn decode(buf: &[u8]) -> Self

Read Self out of an accessor’s @out buffer, consuming whatever the getter handed over.

Safety

buf must be exactly buffer_bytes of a valid Self, owned at +1.

fn encode(&self) -> Vec<u8>

Lay Self out for the setter’s @in argument.

Dyn Compatibility

This trait is not dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety".

Implementations on Foreign Types

impl StoredValue for String

fn metadata() -> *const c_void

fn field_type() -> &'static [u8]

fn mangled() -> &'static str

fn buffer_bytes() -> usize

unsafe fn init_storage(&self, key: &str) -> u64

unsafe fn decode(buf: &[u8]) -> Self

fn encode(&self) -> Vec<u8>

impl StoredValue for bool

fn metadata() -> *const c_void

fn field_type() -> &'static [u8]

fn mangled() -> &'static str

fn buffer_bytes() -> usize

unsafe fn init_storage(&self, key: &str) -> u64

unsafe fn decode(buf: &[u8]) -> Self

fn encode(&self) -> Vec<u8>

impl StoredValue for f64

fn metadata() -> *const c_void

fn field_type() -> &'static [u8]

fn mangled() -> &'static str

fn buffer_bytes() -> usize

unsafe fn init_storage(&self, key: &str) -> u64

unsafe fn decode(buf: &[u8]) -> Self

fn encode(&self) -> Vec<u8>

impl StoredValue for i64

fn metadata() -> *const c_void

fn field_type() -> &'static [u8]

fn mangled() -> &'static str

fn buffer_bytes() -> usize

unsafe fn init_storage(&self, key: &str) -> u64

unsafe fn decode(buf: &[u8]) -> Self

fn encode(&self) -> Vec<u8>

Implementors