gistfile1.js

function setupAsyncValueSwapping(atom,path,asyncValue,promise) {
    var deferred = Q.defer();

    promise
        .then(function asyncCompletionSuccess(data) {
            var swapped = atom.compareAndSwapPathValue(path,asyncValue,asyncValue.toSuccess(data));
            if ( swapped ) {
                deferred.resolve(data);
            } else {
                deferred.reject(new Error("Async value completion for path "+path+" but swap=false"));
            }
        })
        .fail(function asyncCompletionError(error) {
            var swapped = atom.compareAndSwapPathValue(path,asyncValue,asyncValue.toError(error));
            console.error("Async value completion error",path,"Swap success=",swapped);
            console.error(error.stack);
            deferred.reject(error);
        })
        .done();

    return deferred.promise;
};