QmlWeb/Qml.js/Design Questions and Decisions

This page intends to collect questions about software architecute and software design, pros and cons as well as the decisions made on the topic.

Runtime Architecture

Getter/Setter Technique

Possibilities:

C++ style getters and setters: this.width(); and this.setWidth(width);

pro/con: C++ style
pro: fast in all browsers

Transparent getter/setter using Object.defineProperty: Object.defineProperty(this, "width", { get function(){}, set: function(){} });

pro: nice while debugging
con: worse performance in IE
con: horrible performance in Firefox

Transparent getter/setter using literal notation

pro: nice while debugging
con: worse performance in IE
con: you can't use object literals and inheritance at the same time in a standard compliant manner

Benchmark: http://jsperf.com/getter-setter/7

Decision: Use C++ style getters and setters

Storing properties

As we're using setters and getters in either way, we need to store the actual property value separated. There're multiple possibilities for that:

Private member using closures
Private member using like _width
Using property objects and direct object references
Using property indexes and a properties array

pro: If done right, it might provide weak references

Using a properties object and access it per name

con: Bad bad bad performance

Handling bindings

Let the bindings depend on each other and make them set the value on update

pro: Seems logically like the right thing. After all it's the bindings that define the dependencies
con: How to know when a property gets overwritten and thus the binding is invalidated?

Let the properties depend on each other and make them reevaluate the binding when needed

Module Handling

The relevant point here is how to handle the case that in two different contexts, two different modules are loaded, which contain two different types with the same name. The possibilities to handle that are:

Always create a namespace, not only when imported with as
?