Class-specific macros resolve references to class methods, class functions, and class instance data. The macro name or macro parameters contain a class method name, a class function name, an instance variable name, or a class name. The SOM compiler automatically generates and places them in the class Header files. Class implementers can use them by including the class-implementation Header file (.IH) in their source programs. Client programs can use them by including the public class Header file (.H). Because the IH file includes the H file, the class macros defined in the H file are available to both class implementers and clients; and the ones defined in the IH file but not in the H file are available only to class implementers.
The simplest macro is the " _ " (underscore) macro. Object instance data can be referred to by preceding the name of the data element with an underscore character, as shown in the following figure:
return _var1;
Underscored-data-name macros are defined in the H public class Header file and are available to both class implementers and client programs. In addition, instance variables may be accessed by somThisvariable_name, as shown in the following figure:
return somThisvar1;
Object methods can be referred to similarly and invoked by preceding the method name with an underscore ( _ ) character, as shown in the following figure:
/* method A, with parameters x and y, operates on object obj */ _methodA(obj, x, y)
Underscored-method-name macros also are defined in the H public class Header file and are available to both class implementers and client programs. When nonrelated classes independently define methods with the same name, their methods can be invoked with a variation of this macro. The method name is prefixed with the underscore ( _ ) character and class name, as shown in the following figure:
#include "classa.h" #undef _methodA #include "classa.h" /* methodA, defined for ClassA objects, */ /* operates on ClassA instance object obj1 */ ClassA_methodA (obj1); /* methodA, defined for unrelated ClassB objects, */ /* operates on ClassB instance object obj2 */ ClassB_methodA (obj2);
Class objects also can be referred to by preceding the class name with an underscore character. Underscored-class-name macros also are defined in the H public class Header file and are available to both class implementers and client programs.
Other class-specific macros are summarized in the following table:
旼컴컴컴컴컴컴컴컴컴컫컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴� 쿘acros 쿑unction � 쳐컴컴컴컴컴컴컴컴컴컵컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴� 쿌ccess instance data쿲et_<instance variable> � 쳐컴컴컴컴컴컴컴컴컴컵컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴� � �<classname>GetData � 쳐컴컴컴컴컴컴컴컴컴컵컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴� 쿔nstantiate objects �<classname>New � 쳐컴컴컴컴컴컴컴컴컴컵컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴� � �<classname>Renew � 쳐컴컴컴컴컴컴컴컴컴컵컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴� 쿔nvoke methods 쿞OM_Resolve � 쳐컴컴컴컴컴컴컴컴컴컵컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴� � 쿞OM_ResolveNoCheck � 쳐컴컴컴컴컴컴컴컴컴컵컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴� 쿔nvoke methods for �<classname>_parents_<methodname> � 쿮ach parent � � 쳐컴컴컴컴컴컴컴컴컴컵컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴� 쿔nvoke parent �<classname>_parent_<parentclassname> _<methodname>� 쿺ethods � � 쳐컴컴컴컴컴컴컴컴컴컵컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴� 쿟race methods �<classname>MethodDebug � 읕컴컴컴컴컴컴컴컴컴컨컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴�
Of the macros listed in the previous table, <classname>GetData and the parent method macros are defined in the IH file, but not in the H file. They are available only for class implementers.
A class-specific function also is defined in the H file associated with a class. This function, <classname>NewClass, creates the class object. It is invoked automatically when an object is instantiated through the <classname>New class macro.