Using Caché Objects - InterSystems Documentation

Class Projections
class MyApp.Person extends %Persistent [ClassType = persistent]
{
Projection JavaClient As %Projection.Java(ROOTDIR="c:\java");
}
This example defines a projection named “JavaClient” that will use the %Projection.Java
projection class. When the methods of the projection class are called they will be passed the
value of the ROOTDIR parameter.
Note that if you omit the ROOTDIR parameter, your Java or C++ classes will be created
under the default directory specified by your Caché configuration. To set this default directory,
go to the Advanced Settings page of the Portal ([Home] > [Configuration] > [Advanced Settings]);
in the Projections category, for setting you want, click Contents; on the Configuration Settings
page that appears ([Home] > [Configuration] > [Advanced Settings] > [Configuration Settings]),
click Add New Item to display a page where you can specify the default directory for a
namespace.
A class may have any number of uniquely named projections. In the case of multiple projections,
the methods of each projection class will be invoked when a class is compiled or deleted.
The order in which multiple projections are handled is undefined.
16.2 Projection Classes
The behavior of a projection is provided by its corresponding projection class. The projection
class implements a set of methods (the projection interface, q.v.) that are called in response
to certain events during a class' life-cycle.
16.2.1 The Projection Interface
Every projection class implements the projection interface. This interface consists of the
following methods:
CreateProjection
The CreateProjection method is a class method that is invoked by the Class Compiler
after it completes the compilation of a class definition. This method is passed the
name of the class being compiled as well as an array containing the parameter values
(subscripted by parameter name) defined for the projection.
142 Using Caché Objects