Q.bind

q-bind.js

// From discussion at https://groups.google.com/d/msg/q-continuum/68ro20aB358/7kUCAF19qqAJ

// Naive version
function fAsync(a, b) {
    if (a) {
        return Q.reject(new Error());
    }
    if (b) {
        return Q.resolve(42);
    }
    
    return Q.resolve();
}

// With `Q.call`
function fAsync(a, b) {
    return Q.call(function f(a, b) {
        if (a) {
            throw new Error();
        }
        if (b) {
            return 42;
        }
    }, null, a, b);
}

// With `Q.bind`
var fAsync = Q.bind(function f(a, b) {
    if (a) {
        throw new Error();
    }
    if (b) {
        return 42;
    }
});

// Could also pass context, bound args as with `Function.prototype.bind`.

+1 for composability

@ryanwitt Are you on q-continuum? I started the discussion about it over there :)

yes. it's just that i'm anti-social