Path: news.cs.au.dk!not-for-mail
From: "Sascha Kimmel" <kimmel@tricos.com>
Newsgroups: comp.lang.beta
Subject: RE: MB_YESNOCANCEL, MB_YESNO, MB_RETRYCANCEL ...
Date: 1 Mar 1999 22:56:05 -0000
Organization: University of Aarhus, Department of Computer Science (DAIMI)
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Reply-To: "Sascha Kimmel" <kimmel@tricos.com>
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> -----Ursprüngliche Nachricht-----
> Von: Morten Grouleff [mailto:mg@mjolner.dk]
> Gesendet am: Montag, 1. März 1999 13:19
> An: usergroup@mjolner.dk
> Betreff: Re: MB_YESNOCANCEL, MB_YESNO, MB_RETRYCANCEL ...
>
> "Sascha Kimmel" <kimmel@tricos.com> writes:
>
> [...]
>
> > And could someone please explain how to implement certain
> WINAPI functions
> > like the following one in BETA?
> >
> > BOOL GetUserName(
> >   LPTSTR lpBuffer,  // address of name buffer
> >   LPDWORD nSize     // address of size of name buffer
> > );
>
> win32lib/winbase.bet:
>
> (* BOOL WINAPI GetUserNameA (LPSTR lpBuffer,LPDWORD nSize ); *)
> GetUserName: external
>   (# name: @integer;
>      length: @integer;
>      result: @boolean;
>   enter (name, length)
>   do 'GetUserNameA' -> callStd;
>   exit result
>   #);
>
> > My problem is that I don't know how to get the address of a variable.
> > Adresses and addresses.. well, yes, it's C :)
>
> You really should not get the address of an attribbute of a BETA object,
> as it may be changes by the garbage collector.
>
> But there are other ways...:
>
> ORIGIN '~beta/basiclib/betaenv';
> INCLUDE '~beta/sysutils/cstring';
> INCLUDE '~beta/win32lib/winbase';
> --PROGRAM: descriptor--
> (# cs: @CString;
>    lgt, result: @Integer;
> do 256->lgt;
>    lgt->cs.init;
>    (cs, @@lgt)->GetUserName->result;
>    (if result<>0 then
>        cs.get->screen.putLine;
>    if);
>    cs.free;
> #)
>
> Here, CString is used to store the string.  @@lgt is the address of the
> integer lgt.  Note that this code is safe, but only because the address
> is only used in a call of an external function.  Using @@lgt in any
> other way leads to unpredictable errors.  This is not a supported part
> of the implementation and may change without notice.

It's a comparison between an integer and a boolean value, I see. The
compiler gives out a warning telling this.

Thank you for your help.
For someone who needs it (needed for eMail-programs!), here is the code to
get the computer name. INCLUDE and ORIGIN are the same as above, but don't
forget to put "v1.6" there.

(* BOOL WINAPI GetComputerNameA (LPSTR lpBuffer, LPDWORD nSize ); *)
GetComputerNameA:
(#
   cs: @CString;
   t:^text;
   lgt, result: @Integer;
do 256->lgt;
	&text[]->t[];
   lgt->cs.init;
   (cs, @@lgt)->GetComputerName->result;
   (if result<>0 then
       cs.get->t[];
   if);
   cs.free;
   exit t[]
#);


Regards,
S. Kimmel