Win32::OLE::Variant (Perl in a Nutshell, 2nd Edition)

23.4. Win32::OLE::Variant

A Variant is an OLE data structure that contains a type field and a data field. The flags are implemented in Perl (as are many constants) as subroutines that return an integer value. The following table lists the Variant type flags, along with a brief description of each:

Type	Description
`VT_EMPTY`	No value specified. Incidentally, automation does not use `VT_EMPTY` for empty optional parameters. Rather, it uses VT_ERROR with a value of `DISP_E_PARAMNOTFOUND` (which isn't exported by Perl: the value in current Win32 SDK headers is `0x80020004`).
`VT_NULL`	A propagating `NULL` value was specified (not to be confused with a null pointer). This is used for things like the NULL in SQL.
`VT_I2`	A two-byte integer value.
`VT_I4`	A four-byte integer value.
`VT_R4`	An IEEE four-byte real value.
`VT_R8`	An IEEE eight-byte real value.
`VT_CY`	An automation currency value.
`VT_DATE`	An automation date value.
`VT_BSTR`	A string value.
`VT_DISPATCH`	The value contains another automation object.
`VT_ERROR`	An error code was specified. The type of the error is determined by the actual value. As mentioned earlier, this is used to implement empty optional parameters.
`VT_BOOL`	A Boolean (true/false) value. If all bits are `1`, it's true; if all bits are `0`, it's false. Any other value is invalid.
`VT_VARIANT`	The value contains another Variant.
`VT_UNKNOWN`	The value contains an IUnknown pointer (the base class of COM objects).
`VT_UI1`	An unsigned one-byte character.
`VT_BYREF`	Can be combined with some fields to indicate that the data is being passed by reference, rather than by value.
`VT_ARRAY`	The value contains an OLE SAFEARRAY (this flag is not currently exported by Perl).

$vnt = Win32::OLE::Variant->new(type, data);
$vnt = Variant(type, data);

For example, to force a string to be interpreted as a date, create a Variant object and set it to the VT_DATE type:

$dt = Variant(VT_DATE, "August 24, 1970");   # Create an explicit data type
$sheet->Cells(1,1)->{Value} = $dt;           # Set it to a spreadsheet cell

23.4.1. Win32::OLE::Variant Methods

The following methods are defined by Win32::OLE::Variant for working with Variant data types.

$vnt->As(type)

Takes a type flag argument and converts the Variant object to the supplied type before converting it to a Perl value.

ChangeType

$vnt->ChangeType(type)

Takes a type flag argument and converts the Variant object (in place) to the supplied type.

Type

$vnt->Type(  )

Returns the type of the variant $vnt.

Value

$vnt->Value(  )

Returns the value of the variant $vnt as a Perl value. The conversion is performed in the same manner as all return values of Win32::OLE method calls are converted.