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Class Definition Attributes

 The class-specific attributes of a class-definition are as follows:

Attribute Description
Item-configuration
Configuration statements that apply to this item and to all items below it in the workspace hierarchy. Compare with Instance-configuration.
Allowable values:
Described in Chapter 7, Configurations.
Default value:
none


Class-name
The name of the class being added to the class hierarchy.
Allowable values:
Any unique symbol.
Default value:
none


Direct-superior-classes
The names of one or more direct superior classes.
Allowable values:
Any list of class-names.
Default value:
none


Class-specific-attributes
The attributes specific to this class.
Allowable values:
For attribute names, any symbol that is not the name of a system-defined attribute.
Default value:
none


Instance-configuration
Configuration statements that apply to all instances of this class. Compare with Item-configuration.
Allowable values:
Described in Chapter 7, Configurations.
Default value:
none


Change
Changes certain user- and system-defined attribute values.
Allowable values:
Described in Using the Change Attribute.
Default value:
none


Instantiate
Whether the class is can be instantiated. Inapplicable to connections.
Allowable values:
yes, no
Default value:
yes


Include-in-menus
Whether the class appears in the G2 definition menus. Inapplicable to connections.
Allowable values:
yes, no
Default value:
yes


Class-inheritance path
The class inheritance path of the class.
Allowable values:
G2 provided.
Default value:
none


Inherited-attributes
User-defined attributes that the class inherits.
Allowable values:
Any inherited attribute description.
Default value:
none


Initializable-system-attributes
The names of all initializable system attributes inherited from the class's superiors.
Allowable values:
Depend on the particular superiors.
Default value:
none


Attribute-initializations
The default values of some system-defined attributes, and of user-defined inherited attributes.
Allowable values:
See the sectionSpecifying Default Values for Inherited Attributes.
Default value:
none


Icon-description
The textual description of an item's icon. Not applicable to subclasses of connection or message, or other classes that have no iconic representation, such as kb-workspace.
Allowable values:
See Chapter 37, The Icon Editor and Icon Management.
Default value:
inherited

Formatting the Text of Attributes

In some cases, when you enter attributes in a definition table, G2 does not save the formatting characters you enter, such as Control + j for a new line, after you exit from the Text Editor.

In other cases, G2 adds formatting automatically. For example, in the Attributes-specific-to-class attribute, G2 stores each attribute on a separate line, even if you enter multiple attribute names on one line in the Text Editor.

Order of Attributes in Tables

When you create an instance of a user-defined class, the order of attributes in its table is determined by the order in which the attributes are inherited and defined in the class definition. Attributes defined by the class itself appear at the bottom of the table. Those defined by the first direct superior class appear above them, and so on.

The inherited attributes appear in the order that the superior class defined them as class-specific attributes. An item's attribute table lists attributes in this order, from the top of the attribute table to the bottom:

  1. System-defined attributes

  2. User-defined inherited attributes

  3. Class-specific attributes

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Copyright © 1997 Gensym Corporation, Inc.