Packages

The package keyword tells the console that the subsequent block of code is to be declared but not loaded. Packages provide dynamic function-polymorphism in TorqueScript. In short, a function defined in a package will over-ride the prior definition of a same named function when the is activated. When the package is subsequently de-activated, the previous definition of any overridden functions will be re-asserted.

A package has the following syntax:

package package_name
{
   function function_definition0()
   {
      // code
   }
   function function_definitionN()
   {
      // code
   }
};

Some things to know:

• The same function can be defined in multiple packages.
• Only functions can be packaged.
• Datablocks cannot be packaged.
• Packages ‘stack’ meaning that deactivating packages activated prior to the currently active (s) will deactivate all packages activated prior to the being deactivated (see example below).
• Functions in a package may activate and deactivate packages.

In order to use the functions in a package, the package must be activated:

activatePackage(package_name);

Subsequently a package can be deactivated:

deactivatePackage(package_name);

First, define a function and two packages, each of which provides an alternative definition by the same name:

function testFunction()
{
   echo( "testFunction() - unpackaged." );
}
package MyPackage0
{
  function testFunction()
  {
      echo( "testFunction() - MyPackage0." );
  }
};
package MyPackage1
{
  function testFunction()
  {
      echo( "testFunction() - MyPackage1." );
  }
};

Now invoke the testFunction() function from the console under three different conditions:

==> testFunction();
testFunction() - unpackaged.
==> activatePackage( MyPackage0 );
==> testFunction();
testFunction() - MyPackage0.
==> activatePackage( MyPackage1 );
==> testFunction();
testFunction() - MyPackage1.
==> deactivatePackage( MyPackage0 );  // MyPackage1 is automatically deactivated.
==> testFunction();
testFunction() - unpackaged.