[fpc-devel] THandle and 64bit platforms

[Tomas Hajny]

Date sent:      	Mon, 20 Dec 2004 22:50:06 +0100 (CET)
From:           	Michael.VanCanneyt at Wisa.be
To:             	XHajT03 at vol.cz,
	"FPC developers' list" <fpc-devel at lists.freepascal.org>
Subject:        	RE: [fpc-devel] THandle and 64bit platforms
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 .
 .
> > > > > > In the LCL a THandle is used everywhere and in most cases it
> > > > > > represents a pointer. It is also part of the emulated
> > > > > > message records. All members of it are defined as PtrInt. On
> > > > > > placed where a handle is iused, it should map on a PtrInt.
> >  .
> >  .
> In principle, a windows handle is an 'opaque' type. 
> You're not supposed to make any assumptions about it's size or
> internal structure.
> 
> That Windows uses the same handle type for the I/O API and it's GUI
> subsystem is an unfortunate coincidence.

Probably more design decision than "coincidence" - the same type is 
used for everything, not just I/O and GUI, but processes, threads and 
all kinds of system resources too.


> Thinking about it some more I think the more 'correct' choice for
> Lazarus is to introduce a TLCLHandle type, which will be equal to a
> HANDLE (or THANDLE) type on Windows, but which probably will equal a
> pointer under e.g. GTK, and hence a 64-bit pointer on 64-bit
> platforms.
> 
> This will take some work :-)
 .
 .

Would THandle exist on non-Windows platforms under your concept then? 
If so, what would it be on Linux x86-64 (by pure coincidence, of 
course ;-) )?

Tomas