Creating a Data Type Manually: General Steps

This section describes how to create a data type configuration file.

Configuration Files for Data Types

The requirements for configuration files containing data type definitions are:

• The files must use the naming convention name.dt

• The files must be located on the database search path. The default search path is:

  Personal data types—HomeDirectory/.dt/types

  System-wide data types—/etc/dt/appconfig/types/language

  Built-in data types—/usr/dt/appconfig/types/language. You should not use this directory.

  For information on modifying the database search path, see Setting the Value of a Search Path.

To Create a Data Type Definition

1. Open an existing database file or create a new one.

   For more information, see the previous section, Configuration Files for Data Types.

2. Define the data attributes for the data type using the syntax:

   	DATA_ATTRIBUTES data_type_name
    	{
    		ICON						image_name
    		DESCRIPTION				string
    		attribute_field
    		attribute_field
    		…
    	}
   

   where:

   data_type_name—a unique name given to this data type.

   image_name—file name or path of an icon file. Use the base name for the file. For example, for icon files myimage.m.pm and myimage.t.pm, use myimage.

   attribute_field—field that defines the appearance or behavior of the data type.

   string—character string. The contents will be the on-item help for the data type.

   See Example of Creating a Personal Action and Data Type.

3. Define the data criteria for the data type using the syntax:

   	DATA_CRITERIA criteria_name
    	{
    		DATA_ATTRIBUTES_NAME						data_type_name
    		criteria_field
    		criteria_field
    		…
    	}
   

   where:

   criteria_name—unique name for this criteria definition

   data_type_name—name used in the DATA_ATTRIBUTES definition

   criteria_field—field used to define the criteria for assigning a file to this data type

   See Defining the Data Criteria for a Data Type.

4. Save the database file.

5. Create the icons for the data type.

   For more information, see Specifying the Icon Image Used for a Data Type.

6. If necessary, create the actions listed in the ACTIONS field of the attributes definition.

7. Double-click Reload Actions in the Desktop_Tools application group to reload the database.

Example of Creating a Personal Action and Data Type

Suppose your system contains an application named xgif, which displays GIF pictures. Ordinarily, you run the program by executing:

xgif filename

You want to be able to display GIF pictures several ways:

• By double-clicking a GIF data file

• By selecting the data file and choosing the application from the Selected menu

1. Open a new file HomeDirectory/.dt/types/GifViewer.dt for editing.

2. Type the data type definitions:

   	DATA_ATTRIBUTES Gif
    	{
    		DESCRIPTION				Gif image file.
    		ICON						GifIcon
    		ACTIONS					View
    	}
    	DATA_CRITERIA Gif_Criteria
    	{
    		DATA_ATTRIBUTES_NAME			Gif
    		NAME_PATTERN						*.gif
    	}

3. Type the action definition for the GifViewer action:

   	ACTION GifViewer
    	{
    		EXEC_STRING					xgif %(File)Arg_1"Gif file to view:"
    		WINDOW_TYPE					NO_STDIO
    		DESCRIPTION					Double-click or drop a file to \
    										start the Gif viewer.
    	}

   Since the definition does not include an ICON field, the action will use the system's default icon.

4. Type the following map action to connect the GifViewer action to the View action listed in the data type definition. Use the ARG_TYPE field to restrict this view action to Gif-type files.

   	ACTION View
    	{
    		ARG_TYPE				Gif
    		TYPE					MAP
    		MAP_ACTION			GifViewer
    	} 

5. Save the file.

6. Double-click Reload Actions in the Desktop_Tools application group to reread the database.