[STLSoft] Windows Clipboard Library: class clipboard_scope: issue with deallocating string memory
___

Hi Matthew,

I'm trying the small example program for the clipboard_scope class from STLSoft's Windows Clipboard Library. See below.

I encounter the following issues :

1. scope.get_allocator().deallocate( cstr );    // as in doc: old name

2. scope.get_allocator().do_deallocate( cstr ); // do_deallocate: private!

3. shouldn't class clipboard_scope besides scoping the clipboard handle
   also take care of deallocating the memory allocated for the string
   returnd by  scope.get_data( cstr ); ?  (I don't think it does.)

Just to inform you, I'm not depending on it.

Cheers,

Martin.
___

#include <winstl/clipboard/clipboard_scope.hpp>

#include <algorithm>    // std::copy
#include <iostream>     // std::cout, std::endl

int main()
{
   try
   {
      // set the data on the clipboard:
      {
         winstl::clipboard_scope  scope;

         scope.set_data( "Text from clipboard_scope demo." );
      }

      /*
       * as long as no other thread/process changes the clipboard contents
       * in the meanwhile, this can then be read back, as follows:
       */
      {
         winstl::clipboard_scope   scope;
         char const                *cstr;

         scope.get_data( cstr );

         std::cout << "Clipboard data: " << cstr << std::endl;

//         scope.get_allocator().do_deallocate( cstr ); // private!
      }
   }
   catch( std::exception const& e )
   {
      std::cerr << "Exception: " << e.what() << std::endl;
   }
}

// cl -W3 -EHsc -I%STLSOFT%/include winstl_clipboard_scope.cpp user32.lib

Am answering in a rush here, but deallocation is only required when pushing onto the clipboard fails. When it succeeds, the memory
is then owned by the operating system, which will release it at the appropriate time. This is why it uses the global allocator.

If I had written any design documents, this'd be apparent. :$

btw, am very grateful for your continuing interest and efforts on STLSoft, and I hope in a few weeks' time to get time to be able to
lend a hand. ;-)

"Martin Moene" <moene@eld.physics.LeidenUniv.nl> wrote in message news:48501AC7.3000200@eld.physics.LeidenUniv.nl...
> [STLSoft] Windows Clipboard Library: class clipboard_scope: issue with
> deallocating string memory
> ___
>
> Hi Matthew,
>
> I'm trying the small example program for the clipboard_scope class from STLSoft's Windows Clipboard Library. See below.
>
> I encounter the following issues :
>
> 1. scope.get_allocator().deallocate( cstr );    // as in doc: old name
>
> 2. scope.get_allocator().do_deallocate( cstr ); // do_deallocate: private!
>
> 3. shouldn't class clipboard_scope besides scoping the clipboard handle
>     also take care of deallocating the memory allocated for the string
>     returnd by  scope.get_data( cstr ); ?  (I don't think it does.)
>
> Just to inform you, I'm not depending on it.
>
> Cheers,
>
> Martin.
> ___
>
> #include <winstl/clipboard/clipboard_scope.hpp>
>
> #include <algorithm>    // std::copy
> #include <iostream>     // std::cout, std::endl
>
> int main()
> {
>     try
>     {
>        // set the data on the clipboard:
>        {
>           winstl::clipboard_scope  scope;
>
>           scope.set_data( "Text from clipboard_scope demo." );
>        }
>
>        /*
>         * as long as no other thread/process changes the clipboard contents
>         * in the meanwhile, this can then be read back, as follows:
>         */
>        {
>           winstl::clipboard_scope   scope;
>           char const                *cstr;
>
>           scope.get_data( cstr );
>
>           std::cout << "Clipboard data: " << cstr << std::endl;
>
> //         scope.get_allocator().do_deallocate( cstr ); // private!
>        }
>     }
>     catch( std::exception const& e )
>     {
>        std::cerr << "Exception: " << e.what() << std::endl;
>     }
> }
>
> // cl -W3 -EHsc -I%STLSOFT%/include winstl_clipboard_scope.cpp user32.lib

Hi Martin

I've added comments to the get_data() overloads in winstl/clipboard/clipboard_scope.hpp that clarify the resource ownership semantics, and also removed the erroneous line from the class documentation markup

It'll be included in the next release

Thanks

Matt

Martin Moene Wrote:

> [STLSoft] Windows Clipboard Library: class clipboard_scope: issue with
> deallocating string memory
> ___
> 
> Hi Matthew,
> 
> I'm trying the small example program for the clipboard_scope class from STLSoft's Windows Clipboard Library. See below.
> 
> I encounter the following issues :
> 
> 1. scope.get_allocator().deallocate( cstr );    // as in doc: old name
> 
> 2. scope.get_allocator().do_deallocate( cstr ); // do_deallocate: private!
> 
> 3. shouldn't class clipboard_scope besides scoping the clipboard handle
>     also take care of deallocating the memory allocated for the string
>     returnd by  scope.get_data( cstr ); ?  (I don't think it does.)
> 
> Just to inform you, I'm not depending on it.
> 
> Cheers,
> 
> Martin.
> ___
> 
> #include <winstl/clipboard/clipboard_scope.hpp>
> 
> #include <algorithm>    // std::copy
> #include <iostream>     // std::cout, std::endl
> 
> int main()
> {
>     try
>     {
>        // set the data on the clipboard:
>        {
>           winstl::clipboard_scope  scope;
> 
>           scope.set_data( "Text from clipboard_scope demo." );
>        }
> 
>        /*
>         * as long as no other thread/process changes the clipboard contents
>         * in the meanwhile, this can then be read back, as follows:
>         */
>        {
>           winstl::clipboard_scope   scope;
>           char const                *cstr;
> 
>           scope.get_data( cstr );
> 
>           std::cout << "Clipboard data: " << cstr << std::endl;
> 
> //         scope.get_allocator().do_deallocate( cstr ); // private!
>        }
>     }
>     catch( std::exception const& e )
>     {
>        std::cerr << "Exception: " << e.what() << std::endl;
>     }
> }
> 
> // cl -W3 -EHsc -I%STLSOFT%/include winstl_clipboard_scope.cpp user32.lib