=pod

=head1 NAME

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.

=head1 Version 0.18

=head2 VT_CY and VT_DECIMAL return values handled differently

The new C<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);


=head1 Version 0.17

=head2 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
C<vbNullString> constant.


=head1 Version 0.16

=head2 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.

C<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());


=head1 Version 0.13

=head2 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

=head2 New _NewEnum and _Unique options

There are two new options available for the Win32::OLE->Option class
method: C<_NewEnum> provides the elements of a collection object
directly as the value of a C<_NewEnum> property.  The C<_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.


=head1 Version 0.12

=head2 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 C<On Error Goto
Label> construct:

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

  CheckError:
    # ... your error handling code here ...

=head2 Builtin event loop

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

    my $Quit;
    #...
    until ($Quit) {
        Win32::OLE->SpinMessageLoop;
        Win32::Sleep(100);
    }
    package BrowserEvents;
    sub OnQuit { $Quit = 1 }

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

    Win32::OLE->MessageLoop();

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

=head2 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 B<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:

    Win32::OLE->FreeUnusedLibraries();

=head2 The "Win32::OLE" article from "The Perl Journal #10"

The article is Copyright 1998 by I<The Perl
Journal>. http://www.tpj.com

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

=head2 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.

=head2 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.

=head2 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.


=head1 Version 0.11 (changes since 0.1008)

=head2 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
F<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.

=head2 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.

=head1 Version 0.1008

=head2 new LetProperty() object method

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

  $Object->{Property} = $OtherObject;

corresponds to this Visual Basic statement:

  Set Object.Property = OtherObject

To get the I<by value> treatment of the Visual Basic C<Let> statement

  Object.Property = OtherObject

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

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

=head2 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
  }

=head1 Version 0.1007 (changes since 0.1005)

=head2 OLE Event support

This version of Win32::OLE contains B<ALPHA> level support for OLE events. The
userinterface 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:

  Win32::OLE->WithEvents(OBJECT, HANDLER, INTERFACE)

Please read further documentation in Win32::OLE.

=head2 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.

=head2 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.

=head2 Enumerate all Win32::OLE objects

This class method returns the number Win32::OLE objects currently in
existance. 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.

=head2 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:

  $Array->Put(0,0,$First_value)->Put(0,1,$Another_value);

=head2 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:

  $Array->Put(1,0,1);
  $Array->Put(1,1,2);
  $Array->Put(2,0,3);
  $Array->Put(2,1,4);

=head2 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

=head2 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.

=head2 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.

=head2 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
C<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 I<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.

=head1 Version 0.1005 (changes since 0.1003)

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

=head2 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 C<impolite> to stop applications that you did not
start yourself.

=head2 new Variant object method: $object->Copy()

See L<Win32::OLE::Variant/Copy([DIM])>.

=head2 new Win32::OLE->Option() class method

The Option() class method can be used to inspect and modify
L<Win32::OLE/Module Options>. 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 C<Warn>.

=cut
