ITT Rule IDL Version 7.0 User Manual download pdf (Page 54)

54 Chapter 3: Data Management

iTool Data Types iTool Developer’s Guide

iTool Data Types

Every iTool data item (IDLitData object or IDLitDataContainer object) has an

associated iTool data type. The iTool data type of a data item is specified via the

TYPE property of the data object, which can contain any scalar string.

Note

Do not confuse iTool data types with IDL’s inherent data types — integers and

floating-point integers of various sizes and precisions, strings, structures, pointers,

and object references. iTool data types are used only by the iTool system when

matching data objects with the parameters expected by a visualization or operation.

IDL data types describe how a value or values are stored in computer memory.

iTool data types need not correspond directly to an IDL data type.

iTool data typing allows the iTool system to match up data objects with visualization

parameters even if the data objects have not been explicitly associated with the

visualization parameters. Similarly, an iTool operation may apply only to specific

forms of data; the iTool data typing mechanism allows an operation to “see” only

data of the appropriate type.

Composite Data Types

Because IDLitData objects can be collected in IDLitDataContainer objects (and, by

extension, IDLitParameterSet objects), it is possible that data objects with different

iTool data types will be collected in a single container. The iTool data typing system

allows these heterogeneous data sets to be named with unique iTool data types that

reflect the contents of the container. For example, you might define a data container

that contains IDLitData objects with the iTool data types of IDLVECTOR and

IDLARRAY2D with your own iTool data type, such as MY_PLOT.

Data Types of iTool Components

Since the iTool data type of a data item can be any scalar string value, it is up to the

iTool developer to ensure that a data object assigned a given iTool data type contains

the data expected by visualizations and operations that accept that type.

Visualizations or operations that accept an iTool data type are written to act on data

items that have specific IDL data types (or collections of specific IDL data types, in

the case of compound data types). If the data object contains data in a format not

expected by the visualization or operation, errors or unexpected behaviors may result.

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ITT Rule IDL Version 7.0 User Manual Page 54