Enum js::jsapi::OnNewGlobalHookOption [−] [src]

#[repr(u32)]
pub enum OnNewGlobalHookOption {
    FireOnNewGlobalHook,
    DontFireOnNewGlobalHook,
}

During global creation, we fire notifications to callbacks registered via the Debugger API. These callbacks are arbitrary script, and can touch the global in arbitrary ways. When that happens, the global should not be in a half-baked state. But this creates a problem for consumers that need to set slots on the global to put it in a consistent state.

This API provides a way for consumers to set slots atomically (immediately after the global is created), before any debugger hooks are fired. It's unfortunately on the clunky side, but that's the way the cookie crumbles.

If callers have no additional state on the global to set up, they may pass |FireOnNewGlobalHook| to JS_NewGlobalObject, which causes that function to fire the hook as its final act before returning. Otherwise, callers should pass |DontFireOnNewGlobalHook|, which means that they are responsible for invoking JS_FireOnNewGlobalObject upon successfully creating the global. If an error occurs and the operation aborts, callers should skip firing the hook. But otherwise, callers must take care to fire the hook exactly once before compiling any script in the global's scope (we have assertions in place to enforce this). This lets us be sure that debugger clients never miss breakpoints.