#[repr(transparent)]
pub struct Global(_);
Expand description

A WebAssembly global value which can be read and written to.

A global in WebAssembly is sort of like a global variable within an Instance. The global.get and global.set instructions will modify and read global values in a wasm module. Globals can either be imported or exported from wasm modules.

A Global “belongs” to the store that it was originally created within (either via Global::new or via instantiating a Module). Operations on a Global only work with the store it belongs to, and if another store is passed in by accident then methods will panic.

Implementations

Creates a new WebAssembly global value with the provide type ty and initial value val.

The store argument will be the owner of the Global returned. Using the returned Global other items in the store may access this global. For example this could be provided as an argument to Instance::new or Linker::define.

Errors

Returns an error if the ty provided does not match the type of the value val, or if val comes from a different store than store.

Examples
let engine = Engine::default();
let mut store = Store::new(&engine, ());

let ty = GlobalType::new(ValType::I32, Mutability::Const);
let i32_const = Global::new(&mut store, ty, 1i32.into())?;
let ty = GlobalType::new(ValType::F64, Mutability::Var);
let f64_mut = Global::new(&mut store, ty, 2.0f64.into())?;

let module = Module::new(
    &engine,
    "(module
        (global (import \"\" \"i32-const\") i32)
        (global (import \"\" \"f64-mut\") (mut f64))
    )"
)?;

let mut linker = Linker::new(&engine);
linker.define("", "i32-const", i32_const)?;
linker.define("", "f64-mut", f64_mut)?;

let instance = linker.instantiate(&mut store, &module)?;
// ...

Returns the underlying type of this global.

Panics

Panics if store does not own this global.

Returns the current Val of this global.

Panics

Panics if store does not own this global.

Attempts to set the current value of this global to Val.

Errors

Returns an error if this global has a different type than Val, if it’s not a mutable global, or if val comes from a different store than the one provided.

Panics

Panics if store does not own this global.

Trait Implementations

Returns a copy of the value. Read more

Performs copy-assignment from source. Read more

Formats the value using the given formatter. Read more

Performs the conversion.

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.

Calls U::from(self).

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

The alignment of pointer.

The type for initializers.

Initializes a with the given initializer. Read more

Dereferences the given pointer. Read more

Mutably dereferences the given pointer. Read more

Drops the object pointed to by the given pointer. Read more

Should always be Self

The resulting type after obtaining ownership.

Creates owned data from borrowed data, usually by cloning. Read more

🔬 This is a nightly-only experimental API. (toowned_clone_into)

Uses borrowed data to replace owned data, usually by cloning. Read more

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.