Macro project_uninit::project_ptr_mut [−][src]
macro_rules! project_ptr_mut { ($expr:expr => {$( $($props:tt)=>+ ),* $(,)?}) => { ... }; ($expr:expr => $($props:tt)=>+) => { ... }; }
Unsafe: Given a *mut
pointer to a struct, obtain *mut
pointers to one or more of its fields.
This does not statically check whether multiple pointers to the same data are returned.
This must be used in an unsafe
block or function.
Usage
let mut bob = Person { name: Name { first: "Bob", last: "Jones" }, age: 35, id: (111, 222), }; let bob_ptr: *mut Person = &mut bob; unsafe { // Pointer to a single field: let age: *mut u32 = project_ptr_mut!(bob_ptr => age); *age = 36; // Pointers to multiple fields: let (first, last, id0): (*mut &str, *mut &str, *mut usize) = project_ptr_mut!( bob_ptr => { name => first, name => last, id => 0 } ); *first = "Robert"; *last = "Johns"; *id0 = 444; assert_eq!(bob, Person { name: Name { first: "Robert", last: "Johns" }, age: 36, id: (444, 222), }); }