Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!swrinde!mips!atha!aunro!ersys!bking
From: ersys!bking@nro.cs.athabascau.ca (Barry King)
Newsgroups: comp.os.os2.programmer
Subject: Re: OS/2 C compiler
Keywords: OS/2 'C'
Message-ID: <73wR12w164w@ersys.uucp>
Date: 21 Apr 91 21:48:17 GMT
References: <1991Apr20.190744.6675@unixg.ubc.ca>
Organization: Edmonton Remote Systems, Edmonton, AB, Canada
Lines: 40

ballard@cheddar.ucs.ubc.ca (Alan Ballard) writes:

> In article <1581@integow.uucp> hot@integow.uucp (Roland van Hout) writes:
> >
> >We are UNIX C programmers. We have the possibility to port some of our
> >applications to OS/2 for a client. Is it possible to compile reentrant
> >C programs to save memory or must we implement threads to simulate
> >this capability.
> 1) All OS/2 code is reentrant.  If you are run  more than one copy of the 
>    program, only one copy of the code is loaded.
> 2) If you want to share code among different applications, you create
>    "dynamic link libraries" containing the code. 
> 3) Even if you did need to use threads, you don't need to implement them.
>    OS/2 has built-in threads.
> OS/2 does all this stuff much better than unix.
>  

Whoa.  When you say that all OS/2 code is reentrant, that may be true for 
the operating system, but this is _definitely_ not true for applications 
programs.  Hence the requirement for reentrant libraries like MSC 
LLIBCMT.LIB and the deficiency in Zortech's C++ compiler that does not 
support reentrant code.  Running more than one copy of the program is one 
thing but the code within a given running program is not gauranteed to be 
reentrant unless you code it as such.
 
Same with DLLs - they'll have to be coded to be reentrant with 
appropriate libraries.
 
OS/2 of course has 'built in' threads - each process is at least one 
thread under the PM.  Within an application, it is the programmer who 
determines what runs under separate threads.
 
I'm sure you know this, Allan, but for the benefit of the poster of the 
message to which you replied, I think some clarification is necessary.  I 
found your reply somewhat misleading.
 
Regards!

Barry King             ersys!bking@nro.cs.athabascau.ca
Edmonton Remote Systems:  Serving Northern Alberta since 1982