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From: Holger Tuerk <htuerk00@marvin.informatik.uni-dortmund.de>
Newsgroups: comp.lang.beta
Subject: Re: BetaEnv and SystemEnv
Date: Mon, 14 Jun 1999 11:39:13 +0200
Organization: CS Department, University of Dortmund, Germany
Message-ID: <3764CDC1.19E7@marvin.informatik.uni-dortmund.de>
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Bastian wrote:
> [...]
> code1.bet:
> ORIGIN '....betaenv';
> INCLUDE 'code2.bet'
> -- program: descriptor--
> (#
>   ...
>   Method
> #)
> 
> -------------------------
> code2.bet:
> ORIGIN '....systemenv'
> -- lib: attributes --
> Method: systemenv (# ... #)
> ...
> 
> --------------------------
> 
> I compile Code1.bet. When the program comes to the point that METHOD
> should be called, it says that 'Illegal use of SystemEnv. The PROGRAM
> descriptor must be a subpattern of systemenv'.

That is because the only valid approach to use systemenv is

-- program: descriptor --
systemenv
(# ... #)

> I do not think that this is a problem of concurrency !?
> Why does need my slot program be a subpattern of system ? BetaEnv is the
> origin of both Systemenv and further basicsystemenv.

Your program needs to be a specialization of systemenv to be able to use
concurrent methods. These methods must be specializations of system (NOT
systemENV) and should be started with fork. Remind that multithreading
in the MBS currently is cooperative, so do not forget to insert enough
SUSPEND-imperatives.

>[...]