Function comp_state::prelude::use_istate

pub fn use_istate<T: 'static + Clone, F: FnOnce() -> T>(
    data_fn: F
) -> (T, StateAccess<T>)

use_istate() - create a new internal state.

Constructs a T and T accessor pair. T is stored keyed to in a new topological context. The accessor always references this context therefore can you can set/update/ or get this T from anywhere.

If T has already been stored on subsequent revists, T will be a clone of the latest stored T.

As each use_istate() call creates its own context this function can be called any number of times with the same type.

Examples

let (my_string, my_string_access) =  use_istate(|| "foo".to_string());
...
...
 // Maybe in a Callback...
my_string_access.set("bar")

This stores a string "foo" in the current topological context, which is later set to "bar", in some other part of the program.