class Callback
pub class Callback<C>A Lyric closure C calls, with its state: C's void *userdata beside a function pointer.
C is the C function's type as C calls it, extern "C" fn(…) -> T; its first or its last
parameter is the Ptr<void> that C hands back, and the closure takes the others —
Callback<extern "C" fn(Ptr<void>, int) -> void>.new((event) => { seen += event; }), handed
to C as on_event(cb.function, cb.userdata).
The closure stays alive until Callback.release — C may call it as long. C calls it on the thread Lyric runs on, as any function C calls; one that returns nothing may be called on a thread of C's own too, and goes to the thread that made it, which runs it in its scheduler's next turn — with what C passed, while C's thread goes on.
Fields
pub function: CThe pointer C calls: it finds the closure through Callback.userdata.
pub userdata: Ptr<void>What C hands back to Callback.function: the closure's handle.
Methods
pub static fn new(_closure: C): Callback<C>Returns the callback for the closure it is given, a function of the parameters of C but
its userdata. The compiler writes the function C calls; this body never runs.
pub mut fn release(): voidLets the closure go: after it C must not call Callback.function again.
Panics
Where the callback was released already.