SUPAPPLY

SUPAPPLY

Invokes the inherited definition of a method and passes the method's arguments in an SCL list

Category: Object Oriented

Syntax
Details
Example
See Also

Syntax

CALL SUPAPPLY(object-id,method-name,arg-list-id);

return-value=SUPAPPLY(object-id,method-name,arg-list-id);

object-id

contains the identifier of the object for which the method is invoked.

Type: Numeric or Object

method-name

is the name of the method to invoke.

Type: Character

arg-list-id

is the identifier of a list of arguments that are required by the method. An invalid arg-list-id produces an error condition.

Type: Numeric

return-value

contains the value returned by method-name. The data type for return-value should match the data type for the called method.

Type: Numeric, Character, List, Object-name, Class, or Interface

Details

SUPAPPLY provides the same functionality as SUPER except that you can pass arguments to inherited methods in an SCL list. You use SUPAPPLY to execute an inherited method when you define another method that performs additional actions. A method that calls an inherited method and includes additional actions is called an overloaded method. See Overloading Methods for more information.

In Version 8, you must use dot notation to call overloaded methods. Dot notation provides compiler time checking and better performance at run time. With overloaded methods, the compiler must be able to check method signatures in order to call the correct method. For details about dot notation, see Accessing Object Attributes and Methods With Dot Notation.

You can use SUPAPPLY as a function if the called method returns a value with a RETURN statement in the program that defines the method.

Although the method name is typically the name of the currently executing method, which is stored in the system variable _METHOD_, any other method name can be used.

The object identified by object-id must be the same object whose method is currently executing. The identifier for this object is stored in the system variable _SELF_. In methods defined in a CLASS or USECLASS statement block, all references to the class methods and attributes can bypass references to _SELF_.attribute and _SELF_.method(...). For example, to call a super method with dot notation in a method definition, you can use supapply(); , which is equivalent to call supapply(_self_,'m1');.

Example

Consider an Object class in which a Transaction method receives a variable-length parameter list of transactions to record in a table. A subclass of this class records the transactions in an audit trail table that contains two numeric variables, DATETIME and TCOUNT. These variables record the date/time and the number of transactions processed. This example shows the Transaction method, which invokes the inherited Transaction method and then records the size of the transaction (the number of items in the argument list) for a table. The object has the attributes audit, tc_vmum, and dt_vnum. Audit is a table ID for an audit table. Tc_vnum is the variable number for the TCOUNT variable. Dt_vnum is the variable number for the DATETIME variable.

useclass lib.cat.myclass.class;

/* TRANSACT.SCL: TRANSACTION method */
Transaction: method arglist= transactions;   
   call supapply(_self_,'Transaction',transactions);
   if audit then do;
      nTransactions=listlen(transactions);
      call putvarn(audit,tc_vnum,nTransactions);
      call putvarn(audit,dt_vnum,datetime());
      rc=update(audit);
   end;
endmethod;
enduseclass;

This method can be invoked with an arbitrary number of transactions using dot notation, where the SCL variable listOftransactions is an SCL list that contains one or more transaction objects.

dcl lib.cat.myclass.class obj=_NEW_lib.cat.myclass();

obj.Transaction(t1,t2,t3,t4,t5);
obj.Transaction(t1,t2);
obj.Transaction(listOftransactions);

See Also

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