Re: win32ada design question/problem

[Stephen Leake <Stephen.Leake@gsfc.nasa.gov>]

dennison@telepath.com writes:

> In article <364C5EDE.4F402D13@elca-matrix.ch>,
>   Mats.Weber@elca-matrix.ch wrote:
> > 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;
> (snip)
> > 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.
> 
> It wasn't designed at all. (by Ada folk, anway) Its a *thin* binding. If you
> want something that doesn't require unchecked programming to use, then you
> want a thick binding.

While I agree it wasn't well designed, I don't agree you need to go to
a thick binding. The binding should use 'out' parameter modes in the
places where C uses pointers to achieve output parameters. Most
compilers will map an 'out' parameter to a C pointer, since that's
what 'by reference' means.

-- Stephe