Aggregate Mixin

gistfile1.js

function asAggregate() {
  this.applyChange = function(evt, eventName, isFromHistory) {
    var aggregate = this
  
    var handler = aggregate[eventName]
  		
    if(handler) {
      handler.call(aggregate, evt)
    }
		
    if(!isFromHistory) {
      this._uncommittedChanges.push(evt)
    }
  }

  this.commitChanges = function() {
    this._uncommittedChanges = []
  }

  this.getUncommittedChanges = function() {
    return this._uncommittedChanges
  }

  this.loadFromHistory = function(history) {
    var aggregate = this
    history.forEach(function(evt) {
      aggregate.applyChange(evt.evt, evt.__type, true)
    })
  }

  this.loadFromSnapshot = function(snapshot) {
    var aggregate = this
    Object.keys(snapshot).forEach(function(key) {
      var val = snapshot[key]
      aggregate[key] = val
    })
  }
}

// Usage
function AggregateInstance() {
  this._uncommittedChanges = []
}
asAggregate.call(AggregateInstance.prototype)