win32ada design question/problem

[Mats Weber <Mats.Weber@elca-matrix.ch>]

I just had a look at the win32ada binding and found that I could not use
it as I would like. Lets take this function as an example:

>     function WriteFile(hFile                 : Win32.Winnt.HANDLE;
>                        lpBuffer              : Win32.LPCVOID;
>                        nNumberOfBytesToWrite : Win32.DWORD;
>                        lpNumberOfBytesWritten: Win32.LPDWORD;
>                        lpOverlapped          : Win32.Winbase.LPOVERLAPPED)
>                                                return Win32.BOOL;

>    type    DWORD      is access all ULONG; 

Now I want to call this from some procedure:

procedure P is

   bytes_Written : aliased ULONG;
   result        : Win32.bool;

begin
   result := WriteFile(..., 
                       lpNumberOfBytesWritten => bytes_Written'Access,
                       ...);
end P;

The problem is that this does not compile because of accessibility
checks (bytes_Written is less global than the access type).

Of course I can use 'Unchecked_Access to circumvent this, but then I
don't think that the binding is well designed if it requires
'Unchecked_Access all over the place in code that uses it.

The samples directory is full of examples that, in order to be able to
use'Access instead of 'Unchecked_Access, declare all parameters to Win32
as global variables, an approach that is totally incompatible with
multitasking programs.

Another problem is the use of the type

> type    PCCH       is access constant CHAR; 

to pass pointers to strings (it is used in e.g. gethostbyname). Now if I
want to use this, what should I do ? Pass an 'Unchecked_Access to the
first element of the string, and the function is going to read the whole
string ? I don't think this is very clean.

Example:

declare
   S : constant String := ...;
begin
   x := gethostbyname(s(s'first'unchecked_access));
end;

or is there a better way ?

Does the win32ada binding really have the above problems, or am I
missing something ?