Copying Variants

In addition to VariantCopyInd, f90VB offers subroutine VariantCopy, which produces a traditional copy of a Variant variable. If the Variant variable contains a Safe Array or a BString, the contained Safe Array or BString is replicated. If the Variant contains a reference to an object interface (i.e. the variant is of type VT_UNKNOWN or VT_DISPATCH) then the reference counter of the interface is incremented (through a call to the interface’s AddRef procedure). Example 3.2 shows how VariantCopy can be used to duplicate a Variant containing a Safe Array.

Example 3.2

!Replicates a Variant containing a Safe Array

use f90VBDefs

use f90VBSafeArrays

use f90VBVariants

implicit none

type(VARIANT)::vrOrig, vrCopy

integer::i,j

real(FLOAT_KIND),pointer,dimension(:,:)::MappedArray

real(FLOAT_KIND),dimension(5,4)::AFortranArray

integer(SAFEARRAY_KIND)::SAHndl

integer(HRESULT_KIND)::iRet

!Fill AFortran Array with random numbers

call random_seed

call random_number(AFortranArray)

!Generate a new safe array using f90VB's 

!automatic array creation facilities

call SafeArrayCreate(SAHndl,VT_R4, AFortranArray)

!Create a variant with a Safe Array

!Note that the Safe Array contained in this variant

!is a copy of the Safe Array in SAHndl. Their values

!are the same, but they are not the same Safe Array

vrOrig = VariantCreate(VT_ARRAY+VT_R4,SAHndl,iRet, VT_ARRAY+VT_R4)

!we don't need SAHndl anymore, so we can destroy it

call SafeArrayDestroy(SAHndl)

!map Safe Array in vrOrig to easily print its values

call SafeArrayAccessData(vrOrig%varVal%parray,MappedArray,iRet)

!print values in the safe array

print *,'Values of Safe Array in vrOrig:'

do i=lbound(MappedArray,1),ubound(MappedArray,1)

    print *,(MappedArray(i,j),j=lbound(MappedArray,2),ubound(MappedArray,2))

enddo

print *,''

!Copy vrOrig to vrCopy

call VariantCopy(vrOrig,vrCopy)

!map Safe Array in vrOrig to easily print its values

call SafeArrayAccessData(vrOrig%varVal%parray,MappedArray,iRet)

!print values in the safe array

print *,'Values of Safe Array in vrCopy:'

do i=lbound(MappedArray,1),ubound(MappedArray,1)

    print *,(MappedArray(i,j),j=lbound(MappedArray,2),ubound(MappedArray,2))

enddo

print *,''

!Destroy the variants, making sure their contents are

!also destroyed and memory is released (this is an

!important step, particularly when the variant contains

!a type that allocates system resources, like Safe Arrays,

!BStrings or object references)

call VariantClear(vrOrig)

call VariantClear(vrCopy)

stop

end

Clearing Variants