Formal Parameter Declaration

A formal parameter declaration can appear in the following:

• "Function Declaration and Definition"

• "Procedure Declaration and Definition"

• "CREATE FUNCTION Statement"

• "CREATE PROCEDURE Statement"

Topics

• Syntax

• Semantics

• Examples

• Related Topics

Syntax

parameter_declaration ::=

See:

• "datatype ::="

• "expression ::="

Semantics

parameter

Name of the formal parameter that you are declaring, which you can reference in the executable part of the subprogram.

IN, OUT, IN OUT

Mode that determines the behavior of the parameter, explained in "Subprogram Parameter Modes". Default: IN.

NOCOPY

Requests that the compiler pass the corresponding actual parameter by reference instead of value (for the difference, see "Subprogram Parameter Passing Methods"). Each time the subprogram is invoked, the optimizer decides, silently, whether to obey or disregard NOCOPY.

The compiler ignores NOCOPY in these cases:

• The actual parameter must be implicitly converted to the data type of the formal parameter.

• The actual parameter is the element of a collection.

• The actual parameter is a scalar variable with the NOT NULL constraint.

• The actual parameter is a scalar numeric variable with a range, size, scale, or precision constraint.

• The actual and formal parameters are records, one or both was declared with %ROWTYPE or %TYPE, and constraints on corresponding fields differ.

• The actual and formal parameters are records, the actual parameter was declared (implicitly) as the index of a cursor FOR LOOP statement, and constraints on corresponding fields differ.

• The subprogram is invoked through a database link or as an external subprogram.

datatype

Data type of the formal parameter that you are declaring. The data type can be a constrained subtype, but cannot include a constraint (for example, NUMBER(2) or VARCHAR2(20).

If datatype is a constrained subtype, the corresponding actual parameter inherits the NOT NULL constraint of the subtype (if it has one), but not the size (see Example 8-10).

expression

Default value of the formal parameter that you are declaring. The data type of expression must be compatible with datatype.

If a subprogram invocation does not specify an actual parameter for the formal parameter, then that invocation evaluates expression and assigns its value to the formal parameter.

If a subprogram invocation does specify an actual parameter for the formal parameter, then that invocation assigns the value of the actual parameter to the formal parameter and does not evaluate expression.

Examples

• Example 2-26, "Assigning Value to Variable as IN OUT Subprogram Parameter"

• Example 8-9, "Formal Parameters and Actual Parameters"

• Example 8-14, "Parameter Values Before, During, and After Procedure Invocation"

• Example 8-15, "OUT and IN OUT Parameter Values After Unhandled Exception"

• Example 8-16, "OUT Formal Parameter of Record Type with Non-NULL Default Value"

• Example 8-20, "Procedure with Default Parameter Values"

• Example 8-21, "Function Provides Default Parameter Value"

• Example 8-22, "Adding Subprogram Parameter Without Changing Existing Invocations"

Related Topics

In this chapter:

• "Function Declaration and Definition"

• "Procedure Declaration and Definition"

In other chapters:

• "Subprogram Parameters"

• "Tune Subprogram Invocations"

• "CREATE FUNCTION Statement"

• "CREATE PROCEDURE Statement"