Visible to Intel only — GUID: GUID-C44DF05D-510C-4B57-837F-F20B70A5A8E3
Visible to Intel only — GUID: GUID-C44DF05D-510C-4B57-837F-F20B70A5A8E3
Define Generic Names for Procedures
An interface block or a GENERIC statement can be used to specify a generic name to reference all of the procedures within the interface block.
The initial line for such an interface block takes the following form:
INTERFACE generic-name
generic-name |
Is the generic name. It can be the same as any of the procedure names in the interface block, or the same as any accessible generic name (including a generic intrinsic name). A generic name can be the same as a derived-type name. In this case, all of the procedures in the interface block must be functions. |
A generic interface can be used to extend or redefine a generic intrinsic procedure.
The procedures that are given the generic name must be the same kind of subprogram: all must be functions, or all must be subroutines.
Any procedure reference involving a generic procedure name must be resolvable to one specific procedure; it must be unambiguous. For more information, see Unambiguous Generic Procedure References.
The following is an example of a procedure interface block defining a generic name:
INTERFACE GROUP_SUBS
SUBROUTINE INTEGER_SUB (A, B)
INTEGER, INTENT(INOUT) :: A, B
END SUBROUTINE INTEGER_SUB
SUBROUTINE REAL_SUB (A, B)
REAL, INTENT(INOUT) :: A, B
END SUBROUTINE REAL_SUB
SUBROUTINE COMPLEX_SUB (A, B)
COMPLEX, INTENT(INOUT) :: A, B
END SUBROUTINE COMPLEX_SUB
END INTERFACE
The three subroutines can be referenced by their individual specific names or by the group name GROUP_SUBS.
The following example shows a reference to INTEGER_SUB:
INTEGER V1, V2
CALL GROUP_SUBS (V1, V2)
Consider the following:
INTERFACE LINE_EQUATION
SUBROUTINE REAL_LINE_EQ(X1,Y1,X2,Y2,M,B)
REAL,INTENT(IN) :: X1,Y1,X2,Y2
REAL,INTENT(OUT) :: M,B
END SUBROUTINE REAL_LINE_EQ
SUBROUTINE INT_LINE_EQ(X1,Y1,X2,Y2,M,B)
INTEGER,INTENT(IN) :: X1,Y1,X2,Y2
INTEGER,INTENT(OUT) :: M,B
END SUBROUTINE INT_LINE_EQ
END INTERFACE
In this example, LINE_EQUATION is the generic name which can be used for either REAL_LINE_EQ or INT_LINE_EQ. Fortran selects the appropriate subroutine according to the nature of the arguments passed to LINE_EQUATION. Even when a generic name exists, you can always invoke a procedure by its specific name. In the previous example, you can call REAL_LINE_EQ by its specific name (REAL_LINE_EQ), or its generic name LINE_EQUATION.