Changes between Version 9 and Version 10 of SimulationSyntax

Timestamp:

Dec 15, 2009, 10:51:14 PM (14 years ago)

Author:

Philip Taylor

Comment:

--

SimulationSyntax

@@ -267 +267 @@
 == Defining component types in JS ==
 
+Now we want a JS implementation of `ICmpExample`. Think up a new name for this component, like `ExampleTwo` (but more imaginative). Then write '''`binaries/data/mods/public/simulation/comonents/ExampleTwo.js`''':
+{{{
+#!js
+function ExampleTwo() {}
+
+ExampleTwo.prototype.Init = function() {
+    ...
+};
+
+ExampleTwo.prototype.Deinit = function() {
+    ...
+};
+
+ExampleTwo.prototype.OnUpdate = function(msg) {
+    ...
+};
+
+Engine.RegisterComponentType(IID_Example, "ExampleTwo", ExampleTwo);
+}}}
+
+This uses JS's ''prototype'' system to create what is effectively a class, called `ExampleTwo`. (If you wrote `new ExampleTwo()`, then JS would construct a new object which inherits from `ExampleTwo.prototype`, and then would call the `ExampleTwo` function with `this` set to the new object. "Inherit" here means that if you read a property (or method) of the object, which is not defined in the object, then it will be read from the prototype instead.)
+
+`Engine.RegisterComponentType` tells the engine to start using the JS class `ExampleTwo`, exposed (in template files etc) with the name `"ExampleTwo"`, and implementing the interface ID `IID_Example` (i.e. the `ICmpExample` interface).
+
+The `Init` and `Deinit` functions are optional. Unlike C++, there are no `Serialize`/`Deserialize` functions - each JS component instance is automatically serialized and restored. (This automatic serialization restricts what you can store as properties in the object - e.g. you cannot store function closures, because they're too hard to serialize. The details should be documented on some other page eventually.)
+
+Instead of `ClassInit` and `HandleMessage`, you simply add functions of the form `On`''`MessageType`''. When you call `RegisterComponentType`, it will find all such functions and automatically subscribe to the messages. The `msg` parameter is usually a straightforward mapping of the relevant `CMessage` class onto a JS object (e.g. `OnUpdate` can read `msg.turnLength`).
+
+== Defining a new message type ==
+
 ...
-
-== Defining a new message type ==