Using Caché Objects - InterSystems Documentation

Method Generators
In addition to these objects, an array variable, %parameter, is provided. This array contains
the values of any class parameters indexed by parameter name. For example,
%parameter("MYPARM"), contains the value of the MYPARM class parameter for the current
class. This variable is provided as an easier alternative to using the list of parameter definitions
available via the %class object.
18.4 Implementing Method Generators
To implement a method generator, do the following:
1. Define a method and set its CodeMode keyword to “objectgenerator” .
2. In the body of the method, write code that will generate the actual method code when
the class is compiled. This code will used the %code object to write out the code. It will
most likely use the other available objects as inputs to decide what code to generate.
The following is an example of a method generator that creates a method that lists the names
of all the properties of the class it belongs to:
ClassMethod ListProperties() [ CodeMode = objectgenerator ]
{
For i = 1:1:%compiledclass.Properties.Count() {
Set prop = %compiledclass.Properties.GetAt(i).Name
Do %code.WriteLine(" Write """ _ prop _ """,!")
}
Do %code.WriteLine(" Quit")
Quit $$$OK
}
This generator will create a method with an implementation similar to:
Write "Name",!
Write "SSN",!
Quit
Note the following about the method generator code:
1. It uses the WriteLine method of the %code object to write lines of code to a stream
containing the actual implementation for the method. (You can also use the Write method
to write text without an end-of-line character).
2. Each line of generated code has a leading space character. This is required as Caché
ObjectScript does not allow commands within the first space of a line. This would not
be the case if our method generator is creating Basic or Java code.
158 Using Caché Objects