Unsubscribe from topic during publish() callback about amplify

[gitgrimbo]

Here is the patch I made to my local copy (grimbo == me), though I'm sure someone could implement it better!

publish():

    publish: function( topic ) {
        var args = slice.call( arguments, 1 ),
            subscription,
            length,
            i = 0,
            ret;

        if ( !subscriptions[ topic ] ) {
            return true;
        }

        for ( length = subscriptions[ topic ].length; i < length; i++ ) {
            subscription = subscriptions[ topic ][ i ];

            // grimbo - added null check
            if (null !== subscription) {
                ret = subscription.callback.apply( subscription.context, args );
            }

            if ( ret === false ) {
                break;
            }
        }

        // grimbo - cull nulls in case a subscription unsubscribed itself (or
        // another subscription) for this topic
        removeNullSubscriptions(topic);

        return ret !== false;
    },

removeNullSubscriptions():

// grimbo - New function to cull null subscriptions
function removeNullSubscriptions(topic) {
    if ( !subscriptions[ topic ] ) {
        return;
    }
    var i = 0,
        subscription;
    while (i < subscriptions[ topic ].length) {
        subscription = subscriptions[ topic ][ i ];
        if (null === subscription) {
            subscriptions[ topic ].splice( i, 1 );
            continue;
        }
        i++;
    }
}

unsubscribe():

    unsubscribe: function( topic, callback ) {
        if ( !subscriptions[ topic ] ) {
            return;
        }

        var length = subscriptions[ topic ].length,
            i = 0,
            // grimbo
            subscription;

        for ( ; i < length; i++ ) {
            // grimbo - test for null
            subscription = subscriptions[ topic ][ i ];
            if ( null !== subscription && subscription.callback === callback ) {
                //subscriptions[ topic ].splice( i, 1 );
                // grimbo - we can't remove because it upsets the publish loop,
                // so just set to null in case unsubscribe is called from within publish (via a subscription)
                subscriptions[ topic ][ i ] = null;
                break;
            }
        }
    }

[warmrobot]

Why don't you give an option to unsubscribe all callbacks of the topic (like in jquery core )? amplify.unsubscribe("items.loaded") for example.

[scottgonzalez]

That's completely unrelated to this issue.