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METHODS - parameters

Quick Reference

Syntax

... { VALUE(p1) | REFERENCE(p1) | p1 }
        typing
[OPTIONAL|{DEFAULT def1}]
    { VALUE(p2) | REFERENCE(p2) | p2 }
        typing
[OPTIONAL|{DEFAULT def2}]
    ...

Addition:

... OPTIONAL|{DEFAULT def}

Effect

Defines formal parameters p1 p2 ... for methods.

VALUE or REFERENCE are used to define whether a parameter p1 p2 ... is passed by value or by reference. If only one name p1 p2 ... is specified, the parameter is passed by reference by default. An input parameter passed by reference must not be changed in the method.

If the addition typing is used, every formal parameter must be typed. The syntax of typing is described in Typing Syntax. The typing of a formal parameter causes the data type to be checked against the typing when an actual parameter is passed. The typing also defines at which operand positions the formal parameter can be used in the method.

Note

If a formal parameter is typed as a reference variable and cannot be changed in the procedure, the type check is performed in the same way as for an up cast. If it can be changed in the procedure, the actual parameter must be compatible with the formal parameter.

Addition

... OPTIONAL|{DEFAULT def}

Effect

OPTIONAL or DEFAULT can be used to define input parameters and input/output parameters as optional parameters, where DEFAULT can be used to specify a replacement parameter def1, def2, ... No actual parameter needs to be specified for an optional parameter when the method is called. The addition OPTIONAL is used to initialize a formal parameter in a type-friendly way, but the addition DEFAULT passes the value and type of the replacement parameter def1 def2 ... to the formal parameter. The replacement parameter def1 def2 ... can be specified as any appropriate data object at this position except for components of boxed components.

If no actual parameter is specified for a generically typed formal parameter with the addition OPTIONAL when it is called, the type of the formal parameter is completed according to fixed rules.