Object Oriented scripting shell

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Introduction

During the implementation phase of the Multiplayer Armory, it was decided to make a scripted system which uses as many Object Oriented (OO) techniques as possible (without altering the engine). This page will describe the scripted scripting shell which is used to this effect.


CfgOO

Classes, their attributes and methods are defined in configs:

  class CfgOO
  {
     //Name used in method prefix
     class SomeClass 
     {
        //All attributes for this class, which will be configured for
        //each instantiated object of this class
        class Attributes 
        {
           //Class name determines the name of the attribute in Logic variable space
           //Initialized with default value for this type
           class someAttribute
           {
              type = "SCALAR"; //Game variable type (see supported types below) (String)
              defaultValue = 0; //Default value [optional] (Any)
           };
        };
  
        //All methods for this class, which will be precompiled and stored in BIS_OO_<Class>_<Method>
        class Methods 
        {
           //Class name determines the name of the method
           class SomeMethod 
           {
              parameterTypes[] = {"STRING", "SCALAR"}; //Types of each parameter, used for validation (Array of String)
              returnType = "SCALAR"; //The default return value is based on this (String)
              script = "path\someMethod.sqf"; //Function implementing the method to precompile (String)
           };
        };
     };
  };


Functions

addClass

This function loads a class in the shell and it precompiles all of its methods. These methods are then stored in global variables with the following name: BIS_OO_<ClassName>_<methodName>.

  //Assuming the function was loaded into BIS_OO_addClass
  className:String call BIS_OO_addClass;


createObject

To instantiate an object of a loaded class, use this function. It will create a Logic object with all of the defined attributes as variables. This function will also automatically call the class' constructor. This constructor will already receive a reference to the created object as parameter, but additional parameters can be provided.

  //The function is automatically loaded into BIS_OO_createObject after adding the first class
  createdObject:Object = [className:String(, parameter1:Any)] call BIS_OO_createObject;


Supported types

These are the data types supported by the OO shell:

  • "SCALAR"
  • "STRING"
  • "BOOL"
  • "ARRAY"
  • "OBJECT"
  • "CONFIG"
  • "GROUP"
  • "TASK"


Sample

Config:

 class CfgOO
 {
   class MyClass 
   {
     class Attributes 
     {
       class myAttribute {type = "SCALAR";};
     };
     class Methods 
     {
       //Constructor method
       class MyClass 
       {
         parameterTypes[] = {"OBJECT"};
         script = "path\data\scripts\classes\MyClass\MyClass.sqf";
       };
       class myMethod 
       {
         parameterTypes[] = {"OBJECT", "SCALAR", "STRING"};
         returnType = "SCALAR";
         script = "path\data\scripts\classes\MyClass\myMethod.sqf";
       };
     };
   };
 };

Script:

 //Precompiles all methods into global variables
 //Naming convention: BIS_OO_<Class>_<method>
 //Here: BIS_OO_MyClass_MyClass and BIS_OO_MyClass_myMethod
 "MyClass" call (compile (preprocessFileLineNumbers "ca\modules_e\oo\data\scripts\functions\addClass.sqf"));
 
 //Creates a Logic with all attributes initialized
 //Invokes the constructor
 private ["_myClassObject"];
 _myClassObject = ["MyClass"] call BIS_OO_createObject;
 
 //Invoking a method and getting an attribute
 private ["_return", "_value"];
 _return = [player, 1, "Hello"] call BIS_OO_MyClass_myMethod;
 _value = _myClassObject getVariable "myAttribute";