| Win32::OLE::Variant - Create and modify OLE VARIANT variables |
Win32::OLE::Variant - Create and modify OLE VARIANT variables
use Win32::OLE::Variant;
my $var = Variant(VT_DATE, 'Jan 1,1970');
$OleObject->{value} = $var;
$OleObject->Method($var);
The IDispatch interface used by the Perl OLE module uses a universal argument type called VARIANT. This is basically an object containing a data type and the actual data value. The data type is specified by the VT_xxx constants.
nothing()nothing() function returns an empty VT_DISPATCH variant. It can be
used to clear an object reference stored in a property
use Win32::OLE::Variant qw(:DEFAULT nothing);
# ...
$object->{Property} = nothing;
This has the same effect as the Visual Basic statement
Set object.Property = Nothing
The nothing() function is not exported by default.
nullstring()nullstring() function returns a VT_BSTR variant with a NULL string
pointer. This is not the same as a VT_BSTR variant with an empty
string ``''. The nullstring() value is the same as the vbNullString
constant in Visual Basic.
The nullstring() function is not exported by default.
Win32::OLE::Variant-new()>
method (see below). This function is exported by default.
For VT_EMPTY and VT_NULL variants, the DATA argument may be omitted. For all non-VT_ARRAY variants DATA specifies the initial value.
To create a SAFEARRAY variant, you have to specify the VT_ARRAY flag in addition to the variant base type of the array elements. In this cases DATA must be a list specifying the dimensions of the array. Each element can be either an element count (indices 0 to count-1) or an array reference pointing to the lower and upper array bounds of this dimension:
my $Array = Win32::OLE::Variant->new(VT_ARRAY|VT_R8, [1,2], 2);
This creates a 2-dimensional SAFEARRAY of doubles with 4 elements: (1,0), (1,1), (2,0) and (2,1).
A special case is the creation of one-dimensional VT_UI1 arrays with a string DATA argument:
my $String = Variant(VT_ARRAY|VT_UI1, "String");
This creates a 6 element character array initialized to ``String''. For backward compatibility VT_UI1 with a string initializer automatically implies VT_ARRAY. The next line is equivalent to the previous example:
my $String = Variant(VT_UI1, "String");
If you really need a single character VT_UI1 variant, you have to create it using a numeric intializer:
my $Char = Variant(VT_UI1, ord('A'));
As(TYPE)As converts the VARIANT to the new type before converting to a
Perl value. This take the current LCID setting into account. For
example a string might contain a ',' as the decimal point character.
Using $variant-As(VT_R8)> will correctly return the floating
point value.
The underlying variant object is NOT changed by this method.
ChangeType(TYPE)Copy([DIM])
my $Var = Variant(VT_I4|VT_ARRAY|VT_BYREF, [1,5], 3);
my $Copy = $Var->Copy;
The type of $Copy is now VT_I4|VT_ARRAY and the value is a copy of
the other SAFEARRAY. Changes to elements of $Var will not be reflected
in $Copy and vice versa.
The Copy method can also be used to extract a single element of a
VT_ARRAY | VT_VARIANT object. In this case the array indices must be
specified as a list DIM:
my $Int = $Var->Copy(1, 2);
$Int is now a VT_I4 Variant object containing the value of element (1,2).
use Win32::OLE::NLS qw(:LOCALE);
LOCALE_NOUSEROVERRIDE tells the method to use the system default currency format for the specified locale, disregarding any changes that might have been made through the control panel application.
The hash reference could contain the following keys:
NumDigits number of fractional digits
LeadingZero whether to use leading zeroes in decimal fields
Grouping size of each group of digits to the left of the decimal
DecimalSep decimal separator string
ThousandSep thousand separator string
NegativeOrder see L<Win32::OLE::NLS/LOCALE_ICURRENCY>
PositiveOrder see L<Win32::OLE::NLS/LOCALE_INEGCURR>
CurrencySymbol currency symbol string
For example:
use Win32::OLE::Variant;
use Win32::OLE::NLS qw(:DEFAULT :LANG :SUBLANG :DATE :TIME);
my $lcidGerman = MAKELCID(MAKELANGID(LANG_GERMAN, SUBLANG_NEUTRAL));
my $v = Variant(VT_CY, "-922337203685477.5808");
print $v->Currency({CurrencySymbol => "Tuits"}, $lcidGerman), "\n";
will print:
-922.337.203.685.477,58 Tuits
LOCALE_NOUSEROVERRIDE system default date format for this locale
DATE_SHORTDATE use the short date format (default)
DATE_LONGDATE use the long date format
DATE_YEARMONTH use the year/month format
DATE_USE_ALT_CALENDAR use the alternate calendar, if one exists
DATE_LTRREADING left-to-right reading order layout
DATE_RTLREADING right-to left reading order layout
The constants are available from the Win32::OLE::NLS module:
use Win32::OLE::NLS qw(:LOCALE :DATE);
The following elements can be used to construct a date format string. Characters must be specified exactly as given below (e.g. ``dd'' not ``DD''). Spaces can be inserted anywhere between formatting codes, other verbatim text should be included in single quotes.
d day of month
dd day of month with leading zero for single-digit days
ddd day of week: three-letter abbreviation (LOCALE_SABBREVDAYNAME)
dddd day of week: full name (LOCALE_SDAYNAME)
M month
MM month with leading zero for single-digit months
MMM month: three-letter abbreviation (LOCALE_SABBREVMONTHNAME)
MMMM month: full name (LOCALE_SMONTHNAME)
y year as last two digits
yy year as last two digits with leading zero for years less than 10
yyyy year represented by full four digits
gg period/era string
For example:
my $v = Variant(VT_DATE, "April 1 99");
print $v->Date(DATE_LONGDATE), "\n";
print $v->Date("ddd',' MMM dd yy"), "\n";
will print:
Thursday, April 01, 1999
Thu, Apr 01 99
Dim()
my @Dim = $Var->Dim;
Now @Dim contains the following list: ([1,5], [0,2]).
Get(DIM)Get returns the value of the variant, just like the
Value method. For VT_ARRAY variants Get retrieves the value of a single
array element. In this case DIM must be a list of array indices. E.g.
my $Val = $Var->Get(2,0);
As a special case for one dimensional VT_UI1|VT_ARRAY variants the Get
method without arguments returns the character array as a Perl string.
print $String->Get, "\n";
IsNothing()IsNullString()LastError()Win32::OLE::Variant-LastError()> method is deprecated.
Please use the Win32::OLE-LastError()> class method instead.
use Win32::OLE::NLS qw(:LOCALE);
LOCALE_NOUSEROVERRIDE tells the method to use the system default number format for the specified locale, disregarding any changes that might have been made through the control panel application.
The hash reference could contain the following keys:
NumDigits number of fractional digits
LeadingZero whether to use leading zeroes in decimal fields
Grouping size of each group of digits to the left of the decimal
DecimalSep decimal separator string
ThousandSep thousand separator string
NegativeOrder see L<Win32::OLE::NLS/LOCALE_INEGNUMBER>
Put method is used to assign a new value to a variant. The value will
be coerced into the current type of the variant. E.g.:
my $Var = Variant(VT_I4, 42);
$Var->Put(3.1415);
This changes the value of the variant to 3 because the type is VT_I4.
For VT_ARRAY type variants the indices for each dimension of the contained SAFEARRAY must be specified in front of the new value:
$Array->Put(1, 1, 2.7);
It is also possible to assign values to *every* element of the SAFEARRAY at
once using a single Put() method call:
$Array->Put([[1,2], [3,4]]);
In this case the argument to Put() must be an array reference and the
dimensions of the Perl list-of-lists must match the dimensions of the
SAFEARRAY exactly.
The are a few special cases for one-dimensional VT_UI1 arrays: The VALUE can be specified as a string instead of a number. This will set the selected character to the first character of the string or to '\0' if the string was empty:
my $String = Variant(VT_UI1|VT_ARRAY, "ABCDE");
$String->Put(1, "123");
$String->Put(3, ord('Z'));
$String->Put(4, '');
This will set the value of $String to "A1CZ\0". If the index is omitted
then the string is copied to the value completely. The string is truncated
if it is longer than the size of the VT_UI1 array. The result will be padded
with '\0's if the string is shorter:
$String->Put("String");
Now $String contains the value ``Strin''.
Put returns the Variant object itself so that multiple Put calls can be
chained together:
$Array->Put(0,0,$First_value)->Put(0,1,$Another_value);
LOCALE_NOUSEROVERRIDE system default time format for this locale
TIME_NOMINUTESORSECONDS don't use minutes or seconds
TIME_NOSECONDS don't use seconds
TIME_NOTIMEMARKER don't use a time marker
TIME_FORCE24HOURFORMAT always use a 24-hour time format
The constants are available from the Win32::OLE::NLS module:
use Win32::OLE::NLS qw(:LOCALE :TIME);
The following elements can be used to construct a time format string. Characters must be specified exactly as given below (e.g. ``dd'' not ``DD''). Spaces can be inserted anywhere between formatting codes, other verbatim text should be included in single quotes.
h hours; 12-hour clock
hh hours with leading zero for single-digit hours; 12-hour clock
H hours; 24-hour clock
HH hours with leading zero for single-digit hours; 24-hour clock
m minutes
mm minutes with leading zero for single-digit minutes
s seconds
ss seconds with leading zero for single-digit seconds
t one character time marker string, such as A or P
tt multicharacter time marker string, such as AM or PM
For example:
my $v = Variant(VT_DATE, "April 1 99 2:23 pm");
print $v->Time, "\n";
print $v->Time(TIME_FORCE24HOURFORMAT|TIME_NOTIMEMARKER), "\n";
print $v->Time("hh.mm.ss tt"), "\n";
will print:
2:23:00 PM
14:23:00
02.23.00 PM
Type()Type method returns the variant type of the contained VARIANT.
Unicode()Unicode method returns a Unicode::String object. This contains
the BSTR value of the variant in network byte order. If the variant is
not currently in VT_BSTR format then a VT_BSTR copy will be produced first.
Value()Value method returns the value of the VARIANT as a Perl value. The
conversion is performed in the same manner as all return values of
Win32::OLE method calls are converted.
The Win32::OLE::Variant package has overloaded the conversion to
string and number formats. Therefore variant objects can be used in
arithmetic and string operations without applying the Value
method first.
The Win32::OLE::Variant class used to have its own set of class variables
like $CP, $LCID and $Warn. In version 0.1003 and later of the
Win32::OLE module these variables have been eliminated. Now the settings
of Win32::OLE are used by the Win32::OLE::Variant module too. Please read
the documentation of the Win32::OLE->Option class method.
These constants are exported by default:
VT_EMPTY
VT_NULL
VT_I2
VT_I4
VT_R4
VT_R8
VT_CY
VT_DATE
VT_BSTR
VT_DISPATCH
VT_ERROR
VT_BOOL
VT_VARIANT
VT_UNKNOWN
VT_DECIMAL
VT_UI1
VT_ARRAY
VT_BYREF
VT_DECIMAL is not on the official list of allowable OLE Automation datatypes. But even Microsoft ADO seems to sometimes return values of Recordset fields in VT_DECIMAL format.
A Variant is a data type that is used to pass data between OLE connections.
The default behavior is to convert each perl scalar variable into an OLE Variant according to the internal perl representation. The following type correspondence holds:
C type Perl type OLE type
------ --------- --------
int IV VT_I4
double NV VT_R8
char * PV VT_BSTR
void * ref to AV VT_ARRAY
? undef VT_ERROR
? Win32::OLE object VT_DISPATCH
Note that VT_BSTR is a wide character or Unicode string. This presents a
problem if you want to pass in binary data as a parameter as 0x00 is
inserted between all the bytes in your data. The Variant() method
provides a solution to this. With Variants the script writer can specify
the OLE variant type that the parameter should be converted to. Currently
supported types are:
VT_UI1 unsigned char
VT_I2 signed int (2 bytes)
VT_I4 signed int (4 bytes)
VT_R4 float (4 bytes)
VT_R8 float (8 bytes)
VT_DATE OLE Date
VT_BSTR OLE String
VT_CY OLE Currency
VT_BOOL OLE Boolean
When VT_DATE and VT_CY objects are created, the input parameter is treated
as a Perl string type, which is then converted to VT_BSTR, and finally to
VT_DATE of VT_CY using the VariantChangeType() OLE API function.
See EXAMPLES in the Win32::OLE manpage for how these types can be used.
A variant can not only contain a single value but also a multi-dimensional
array of values (called a SAFEARRAY). In this case the VT_ARRAY flag must
be added to the base variant type, e.g. VT_I4 | VT_ARRAY for an array of
integers. The VT_EMPTY and VT_NULL types are invalid for SAFEARRAYs. It
is possible to create an array of variants: VT_VARIANT | VT_ARRAY. In this
case each element of the array can have a different type (including VT_EMPTY
and VT_NULL). The elements of a VT_VARIANT SAFEARRAY cannot have either of the
VT_ARRAY or VT_BYREF flags set.
The lower and upper bounds for each dimension can be specified separately. They do not have to have all the same lower bound (unlike Perl's arrays).
Some OLE servers expect parameters passed by reference so that they can be changed in the method call. This allows methods to easily return multiple values. There is preliminary support for this in the Win32::OLE::Variant module:
my $x = Variant(VT_I4|VT_BYREF, 0);
my $y = Variant(VT_I4|VT_BYREF, 0);
$Corel->GetSize($x, $y);
print "Size is $x by $y\n";
After the GetSize method call $x and $y will be set to
the respective sizes. They will still be variants. In the print
statement the overloading converts them to string representation
automatically.
VT_BYREF is now supported for all variant types (including SAFEARRAYs). It can also be used to pass an OLE object by reference:
my $Results = $App->CreateResultsObject;
$Object->Method(Variant(VT_DISPATCH|VT_BYREF, $Results));
This module is part of the Win32::OLE distribution.
| Win32::OLE::Variant - Create and modify OLE VARIANT variables |