Win32::OLE::NEWS - What's new in Win32::OLE

This file contains a history of user visible changes to the Win32::OLE::* modules. Only new features and major bug fixes that might affect backwards compatibility are included.

Version 0.18

VT_CY and VT_DECIMAL return values handled differently

The new Variant option enables values of VT_CY or VT_DECIMAL type to be returned as Win32::OLE::Variant objects instead of being converted into strings and numbers respectively. This is similar to the change in Win32::OLE version 0.12 to VT_DATE and VT_ERROR values. The Win32::OLE::Variant module must be included to make sure that VT_CY and VT_DECIMAL values behave as before in numeric or string contexts.

Because the new behavior is potentially incompatible, it must be explicitly enabled:

    Win32::OLE->Option(Variant => 1);

Version 0.17

New nullstring() function in Win32::OLE::Variant

The nullstring() function returns a VT_BSTR variant containing a NULL string pointer. Note that this is not the same as a VT_BSTR variant containing the empty string "".

The nullstring() return value is equivalent to the Visual Basic vbNullString constant.

Version 0.16

Improved Unicode support

Passing Unicode strings to methods and properties as well as returning Unicode strings back to Perl works now with both Perl 5.6 and 5.8. Note that the Unicode support in 5.8 is much more complete than in 5.6 or 5.6.1.

Unicode::String objects can now be passed to methods or assigned to properties.

You must enable Unicode support by switching Win32::OLE to the UTF8 codepage:

    Win32::OLE->Option(CP => Win32::OLE::CP_UTF8());

Version 0.13

New nothing() function in Win32::OLE::Variant

The 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

New _NewEnum and _Unique options

There are two new options available for the Win32::OLE->Option class method: _NewEnum provides the elements of a collection object directly as the value of a _NewEnum property. The _Unique option guarantees that Win32::OLE will not create multiple proxy objects for the same underlying COM/OLE object.

Both options are only really useful to tree traversal programs or during debugging.

Version 0.12

Additional error handling functionality

The Warn option can now be set to a CODE reference too. For example,

    Win32::OLE->Option(Warn => 3);

could now be written as

    Win32::OLE->Option(Warn => \&Carp::croak);

This can even be used to emulate the VisualBasic On Error Goto Label construct:

    Win32::OLE->Option(Warn =>  sub {goto CheckError});
    # ... your normal OLE code here ...

    # ... your error handling code here ...

Builtin event loop

Processing OLE events required a polling loop before, e.g.

    my $Quit;
    until ($Quit) {
    package BrowserEvents;
    sub OnQuit { $Quit = 1 }

This is inefficient and a bit odd. This version of Win32::OLE now supports a standard messageloop:


    package BrowserEvents;
    sub OnQuit { Win32::OLE->QuitMessageLoop }

Free unused OLE libraries

Previous versions of Win32::OLE would call the CoFreeUnusedLibraries() API whenever an OLE object was destroyed. This made sure that OLE libraries would be unloaded as soon as they were no longer needed. Unfortunately, objects implemented in Visual Basic tend to crash during this call, as they pretend to be ready for unloading, when in fact, they aren't.

The unloading of object libraries is really only important for long running processes that might instantiate a huge number of different objects over time. Therefore this API is no longer called automatically. The functionality is now available explicitly to those who want or need it by calling a Win32::OLE class method:


The "Win32::OLE" article from "The Perl Journal #10"

The article is Copyright 1998 by The Perl Journal.

It originally appeared in The Perl Journal # 10 and appears here courtesy of Jon Orwant and The Perl Journal. The sample code from the article is in the eg/ file.

VARIANT->Put() bug fixes

The Put() method didn't work correctly for arrays of type VT_BSTR, VT_DISPATH or VT_UNKNOWN. This has been fixed.

Error message fixes

Previous versions of Win32::OLE gave a wrong argument index for some OLE error messages (the number was too large by 1). This should be fixed now.

VT_DATE and VT_ERROR return values handled differently

Method calls and property accesses returning a VT_DATE or VT_ERROR value would previously translate the value to string or integer format. This has been changed to return a Win32::OLE::Variant object. The return values will behave as before if the Win32::OLE::Variant module is being used. This module overloads the conversion of the objects to strings and numbers.

Version 0.11 (changes since 0.1008)

new DHTML typelib browser

The Win32::OLE distribution now contains a type library browser. It is written in PerlScript, generating dynamic HTML. It requires Internet Explorer 4.0 or later. You'll find it in browser/Browser.html. It should be available in the ActivePerl HTML help under Win32::OLE::Browser.

After selecting a library, type or member you can press F1 to call up the corresponding help file at the appropriate location.

VT_DECIMAL support

The Win32::OLE::Variant module now supports VT_DECIMAL variants too. They are not "officially" allowed in OLE Automation calls, but even Microsoft's "ActiveX Data Objects" sometimes returns VT_DECIMAL values.

VT_DECIMAL variables are stored as 96-bit integers scaled by a variable power of 10. The power of 10 scaling factor specifies the number of digits to the right of the decimal point, and ranges from 0 to 28. With a scale of 0 (no decimal places), the largest possible value is +/-79,228,162,514,264,337,593,543,950,335. With a 28 decimal places, the largest value is +/-7.9228162514264337593543950335 and the smallest, non-zero value is +/-0.0000000000000000000000000001.

Version 0.1008

new LetProperty() object method

In Win32::OLE property assignment using the hash syntax is equivalent to the Visual Basic Set syntax (by reference assignment):

  $Object->{Property} = $OtherObject;

corresponds to this Visual Basic statement:

  Set Object.Property = OtherObject

To get the by value treatment of the Visual Basic Let statement

  Object.Property = OtherObject

you have to use the LetProperty() object method in Perl:

  $Object->LetProperty($Property, $OtherObject);

new HRESULT() function

The HRESULT() function converts an unsigned number into a signed HRESULT error value as used by OLE internally. This is necessary because Perl treats all hexadecimal constants as unsigned. To check if the last OLE function returned "Member not found" (0x80020003) you can write:

  if (Win32::OLE->LastError == HRESULT(0x80020003)) {
      # your error recovery here

Version 0.1007 (changes since 0.1005)

OLE Event support

This version of Win32::OLE contains ALPHA level support for OLE events. The user interface is still subject to change. There are ActiveX objects / controls that don't fire events under the current implementation.

Events are enabled for a specific object with the Win32::OLE->WithEvents() class method:


Please read further documentation in Win32::OLE.

GetObject() and GetActiveObject() now support optional DESTRUCTOR argument

It is now possible to specify a DESTRUCTOR argument to the GetObject() and GetActiveObject() class methods. They work identical to the new() DESTRUCTOR argument.

Remote object instantiation via DCOM

This has actually been in Win32::OLE since 0.0608, but somehow never got documented. You can provide an array reference in place of the usual PROGID parameter to Win32::OLE->new():

  OBJ = Win32::OLE->new([MACHINE, PRODID]);

The array must contain two elements: the name of the MACHINE and the PROGID. This will try to create the object on the remote MACHINE.

Enumerate all Win32::OLE objects

This class method returns the number Win32::OLE objects currently in existence. It will call the optional CALLBACK function for each of these objects:

  $Count = Win32::OLE->EnumAllObjects(sub {
      my $Object = shift;
      my $Class = Win32::OLE->QueryObjectType($Object);
      printf "# Object=%s Class=%s\n", $Object, $Class;

The EnumAllObjects() method is primarily a debugging tool. It can be used e.g. in an END block to check if all external connections have been properly destroyed.

The VARIANT->Put() method now returns the VARIANT object itself

This allows chaining of Put() method calls to set multiple values in an array variant:


The VARIANT->Put(ARRAYREF) form allows assignment to a complete SAFEARRAY

This allows automatic conversion from a list of lists to a SAFEARRAY. You can now write:

  my $Array = Variant(VT_ARRAY|VT_R8, [1,2], 2);
  $Array->Put([[1,2], [3,4]]);

instead of the tedious:


New Variant formatting methods

There are four new methods for formatting variant values: Currency(), Date(), Number() and Time(). 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

new Win32::OLE::NLS methods: SendSettingChange() and SetLocaleInfo()

SendSettingChange() sends a WM_SETTINGCHANGE message to all top level windows.

SetLocaleInfo() allows changing elements in the user override section of the locale database. Unfortunately these changes are not automatically available to further Variant formatting; you have to call SendSettingChange() first.

Win32::OLE::Const now correctly treats version numbers as hex

The minor and major version numbers of type libraries have been treated as decimal. This was wrong. They are now correctly decoded as hex.

more robust global destruction of Win32::OLE objects

The final destruction of Win32::OLE objects has always been somewhat fragile. The reason for this is that Perl doesn't honour reference counts during global destruction but destroys objects in seemingly random order. This can lead to leaked database connections or unterminated external objects. The only solution was to make all objects lexical and hope that no object would be trapped in a closure. Alternatively all objects could be explicitly set to undef, which doesn't work very well with exception handling.

With version 0.1007 of Win32::OLE this problem should be gone: The module keeps a list of active Win32::OLE objects. It uses an END block to destroy all objects at program termination before the Perl's global destruction starts. Objects still existing at program termination are now destroyed in reverse order of creation. The effect is similar to explicitly calling Win32::OLE->Uninitialize() just prior to termination.

Version 0.1005 (changes since 0.1003)

Win32::OLE 0.1005 has been release with ActivePerl build 509. It is also included in the Perl Resource Kit for Win32 Update.

optional DESTRUCTOR for GetActiveObject() GetObject() class methods

The GetActiveObject() and GetObject() class method now also support an optional DESTRUCTOR parameter just like Win32::OLE->new(). The DESTRUCTOR is executed when the last reference to this object goes away. It is generally considered impolite to stop applications that you did not start yourself.

new Variant object method: $object->Copy()

See "Copy([DIM])" in Win32::OLE::Variant.

new Win32::OLE->Option() class method

The Option() class method can be used to inspect and modify "Module Options" in Win32::OLE. The single argument form retrieves the value of an option:

  my $CP = Win32::OLE->Option('CP');

A single call can be used to set multiple options simultaneously:

  Win32::OLE->Option(CP => CP_ACP, Warn => 3);

Currently the following options exist: CP, LCID and Warn.