Calling the Routines Generated by the Module Wizard (Windows*)

This topic only applies to Windows* operating systems.

Although Standard Fortran does not support objects, it does provide Standard Fortran modules. A module is a set of declarations that are grouped together under a global name, and are made available to other program units by using the USE statement.

The Intel® Fortran Module Wizard generates a source file containing one or more modules. The types of information placed in the modules include:

• Derived-type definitions are Fortran equivalents of data structures that are found in the type information.

• Constant definitions are Fortran PARAMETER declarations that include identifiers and enumerations found in the type information.

• Procedure interface definitions are Fortran interface blocks that describe the procedures found in the type information.

• Procedure definitions are Fortran functions and subroutines that are jacket routines for the procedures found in the type information.

The jacket routines make the external procedures easier to call from Fortran by handling data conversion and low-level invocation details.

The use of modules allows the Intel® Fortran Module Wizard to encapsulate the data structures and procedures exposed by an object or DLL in a single place. You can then share these definitions in multiple Fortran programs.

The appropriate USE statement needs to be added in your program, as well as function invocations or subroutine calls.

The routines generated by the Intel® Fortran Module Wizard are designed to be called from Fortran. These routines in turn call the appropriate system routines (not designed to be called from Fortran), thereby simplifying the coding needed to use COM and Automation objects.

Intel® Visual Fortran provides a set of run-time routines that present to the Fortran programmer a higher level abstraction of the COM and Automation functionality. The Fortran interfaces that the wizard generates hide most of the differences between Automation objects and COM objects.

Depending on the options specified, the following routines can be present in the generated code:

The following code shows an annotated version of a portion of the code generated by the Intel® Fortran Module Wizard. This code is generated from the COM type information for the Save method of the IGeneric Document interface.

 INTERFACE
 !  Saves the document to disk.         1
 INTEGER*4 FUNCTION IGenericDocument_Save($OBJECT, vFilename, &
					vBoolPrompt, pSaved)         2 
 USE IFWINTY
 INTEGER (INT_PTR_KIND()), INTENT(IN) :: $OBJECT     ! Object Pointer
 
 !DIR$ ATTRIBUTES VALUE	:: $OBJECT                                   3 
 TYPE (VARIANT), INTENT(IN), OPTIONAL :: vFilename   ! (Optional Arg)         4 
 !DIR$ ATTRIBUTES REFERENCE      :: vFilename
 TYPE (VARIANT), INTENT(IN), OPTIONAL :: vBoolPrompt ! (Optional Arg)
 !DIR$ ATTRIBUTES REFERENCE      :: vBoolPrompt
 INTEGER, INTENT(OUT) :: pSaved          ! DsSaveStatus               5 
 !DIR$ ATTRIBUTES REFERENCE  :: pSaved
 !DIR$ ATTRIBUTES STDCALL    :: IGenericDocument_Save
 END FUNCTION IGenericDocument_Save
 END INTERFACE
 POINTER(IGenericDocument_Save_PTR, IGenericDocument_Save) ! routine pointer 6

Notes for this example:

¹ If the type information provides a comment that describes the member function, then the comment is placed before the beginning of the procedure.

² The first argument to the procedure is always $OBJECT. It is a pointer to the object's interface. The remaining argument names are determined from the type information. For information on how to get a pointer to an object's interface, see Getting a Pointer to an Objects Interface.

³ This is an example of an ATTRIBUTES directive statement used to specify the calling convention of an argument.

⁴ A VARIANT is a data structure that can contain any type of Automation data. It contains a field that identifies the type of data and a union that holds the data value. The use of a VARIANT argument allows the caller to use any data type that can be converted into the data type expected by the member function.

⁵ Nearly every COM member function returns a status of type HRESULT. Because of this, if a COM member function produces output, it uses output arguments to return the values. In this example, the "pSaved" argument returns a routine specific status value.

⁶ The interface of a COM member function looks very similar to the interface for a dynamic link library function with one major exception. Unlike a DLL function, the address of a COM member function is never known at program link time. You must get a pointer to an object's interface at run-time, and the address of a particular member function is computed from that.

The following code shows an annotated version of the wrapper generated by the Intel® Fortran Module Wizard for the "Save" function. The name of a wrapper is the same as the name of the corresponding member function, prefixed with a "$" character.

 ! Saves the document to disk.
  INTEGER*4 FUNCTION $IGenericDocument_Save($OBJECT, vFilename, &  1
			vBoolPrompt, pSaved)
  IMPLICIT NONE
  INTEGER(INT_PTR_KIND()), INTENT(IN) :: $OBJECT    ! Object Pointer
  !DIR$ ATTRIBUTES VALUE :: $OBJECT
  TYPE (VARIANT), INTENT(IN), OPTIONAL :: vFilename
  !DIR$ ATTRIBUTES REFERENCE :: vFilename
  TYPE (VARIANT), INTENT(IN), OPTIONAL :: vBoolPrompt
  !DIR$ ATTRIBUTES REFERENCE :: vBoolPrompt
  INTEGER, INTENT(OUT)	:: pSaved	! DsSaveStatus
  !DIR$ ATTRIBUTES REFERENCE :: pSaved
  INTEGER(4) $RETURN
  INTEGER(INT_PTR_KIND()) $VTBL		    ! Interface Function Table    2 
  POINTER($VPTR, $VTBL)
  TYPE (VARIANT) :: $VAR_vFilename
  TYPE (VARIANT) :: $VAR_vBoolPrompt
  IF (PRESENT(vFilename)) THEN                                   3 
    $VAR_vFilename = vFilename
  ELSE
    $VAR_vFilename = OPTIONAL_VARIANT
  END IF
  IF (PRESENT(vBoolPrompt)) THEN
    $VAR_vBoolPrompt = vBoolPrompt
  ELSE
   $VAR_vBoolPrompt = OPTIONAL_VARIANT
  END IF
  $VPTR = $OBJECT		   ! Interface Function Table     4 
  $VPTR = $VTBL + 84	! Add routine table offset
  IGenericDocument_Save_PTR = $VTBL
  $RETURN = IGenericDocument_Save($OBJECT, $VAR_vFilename, &
  $VAR_vBoolPrompt, pSaved)
  $IGenericDocument_Save = $RETURN
  END FUNCTION $IGenericDocument_Save

Notes for this example:

¹ The wrapper takes the same argument names as the member function interface.

² The wrapper computes the address of the member function from the interface pointer and an offset found in the interface's type information. In implementation terms, an interface pointer is a pointer to a pointer to an array of function pointers called an "Interface Function Table."

³ Arguments to a COM or Automation routine can be optional. The wrapper handles the invocation details for specifying an optional argument that is not present in the call.

⁴ The offset of the "Save" member function is 84. The code assigns the computed address to the function pointer IGenericDocument_Save_PTR, which was declared with the interface shown above, and then calls the function.

The following code shows an annotated version of a portion of the code generated by the Intel® Fortran Module Wizard from Automation type information for the Rebuild All method of the IApplication interface.

 ! Rebuilds all files in a specified configuration.
 SUBROUTINE IApplication_RebuildAll($OBJECT, Configuration, $STATUS) 1 
 IMPLICIT NONE
 INTEGER(INT_PTR_KIND()), INTENT(IN)            :: $OBJECT        ! Object Pointer
 !DIR$ ATTRIBUTES VALUE           :: $OBJECT
 TYPE (VARIANT), INTENT(IN), OPTIONAL :: Configuration
 !DIR$ ATTRIBUTES REFERENCE          :: Configuration
 INTEGER(4), INTENT(OUT), OPTIONAL    :: $STATUS       ! Method status
 !DIR$ ATTRIBUTES REFERENCE          :: $STATUS
 INTEGER(4) $$STATUS
 INTEGER (INT_PTR_KIND) invokeargs
 invokeargs = AUTOALLOCATEINVOKEARGS()                       2 
 IF (PRESENT(Configuration)) CALL AUTOADDARG(invokeargs, '$ARG1', &
			Configuration, AUTO_ARG_IN)
 $$STATUS = AUTOINVOKE($OBJECT, 28, invokeargs)              3 
 IF (PRESENT($STATUS)) $STATUS = $$STATUS                    4 
 CALL AUTODEALLOCATEINVOKEARGS (invokeargs)                  5 
 END SUBROUTINE IApplication_RebuildAll

Notes for this example:

¹The first argument to the procedure is always $OBJECT. It is a pointer to an Automation object's IDispatch interface. The last argument to the procedure is always $STATUS. It is an optional argument that you can specify if you wish to examine the return status of the method. The IDispatch Invoke member function returns a status of type HRESULT. An HRESULT is a 32-bit value. It has the same structure as a Windows error code. In between the $OBJECT and $STATUS arguments are the method arguments' names determined from the type information. Sometimes, the type information does not provide a name for an argument. The Fortran Module Wizard creates a "$ARGn" name in this case.

² AUTOAllocateInvokeArgs allocates a data structure that is used to collect the arguments that you will pass to the method. AUTOAddArg adds an argument to this data structure.

³ AUTOInvoke invokes the named method passing the argument list. This returns a status result.

⁴ If the caller supplied a status argument, the code copies the status result to it.

⁵AUTODeallocateInvokeArgs deallocates the memory used by the argument list data structure.