export function invokeCommand<TObj extends ReactiveObject, TArg, TResult>(source: Observable<TArg>, obj: TObj, command: string | ReactiveCommand<TArg, TResult>): Observable<TResult> {
var commandObservable: Observable<ReactiveCommand<TArg, TResult>>;
var canExecute: Observable<boolean>;
var isExecuting: Observable<boolean>;
if (typeof command === "string") {
// Make sure that the current command is observed
commandObservable = obj.whenSingle(command, true).map(e => e.newPropertyValue);
canExecute = commandObservable.map(c => c.canExecute).switch();
} else {
commandObservable = Observable.of(command);
canExecute = command.canExecute;
}
var results = source
.withLatestFrom(commandObservable, canExecute, (v1, command, canExecute) => {
return {
canExecute,
command,
observedValue: v1
};
})
.filter(o => o.canExecute && o.command != null)
.distinctUntilChanged()
.flatMap(o => {
return o.command.execute(o.observedValue);
});
return results;
}