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.

Defining the Data Attributes of a Data Type

The DATA_ATTRIBUTES definition defines the appearance and behavior of the data type. It specifies the name of the data type, and provides the ability to specify:

• The File Manager icon (ICON field)

• The double-click behavior and contents of the Selected menu (ACTIONS field)

• The data type's on-item help (DESCRIPTION field)