182 Chapter 7: Creating an Operation
Registering an Operation iTool Developer’s Guide
Registering an Operation
Before an operation can be performed by an iTool, the operation’s class definition
must be registered as being available to the iTool. Registering an operation with the
iTool links the class definition file that contains the actual IDL code that defines the
operation with a simple string that names the type. Code that performs an operation in
an iTool uses the name string to specify which operation should be performed.
Using IDLitTool::RegisterOperation
In most cases, you will register an operation with the iTool in the iTool’s class Init
method. Registration ensures that the operation is available to the iTool. (See
“Creating a New iTool Class” on page 91 for details on the iTool class Init method.)
To register an operation, call the IDLitTool::RegisterOperation method:
self->RegisterOperation,
OperationName
,
Operation_Class_Name
where OperationName is the string you will use when referring to the operation, and
Operation_Class_Name is a string that specifies the name of the class file that
contains the operation’s definition.
Note
The file
Operation_Class_Name
__define.pro must exist somewhere in
IDL’s path for the visualization type to be successfully registered.
See “IDLitTool::RegisterOperation” (IDL Reference Guide) for details.
Specifying Useful Properties
You can set any property of the IDLitOperation and IDLitComponent classes when
registering an operation. The following properties may be of particular interest:
EXPENSIVE_COMPUTATION
A boolean value that indicates whether the operation is expensive. Expensive
operations are those that require significant memory or processing time to execute.
Individual operations should use the value of this property to determine whether the
results of the operation should be cached to avoid re-execution when undoing or
redoing.
