Newsgroups: comp.lang.c++
Path: utzoo!henry
From: henry@utzoo.uucp (Henry Spencer)
Subject: Re: Eiffel vs. C++
Message-ID: <1989Jun7.223554.309@utzoo.uucp>
Organization: U of Toronto Zoology
References: <2689@ssc-vax.UUCP> <6590138@hplsla.HP.COM> <149@eiffel.UUCP> <233@pink.ACA.MCC.COM> <1989Jun6.171549.16028@utzoo.uucp> <4684@psuvax1.cs.psu.edu>
Date: Wed, 7 Jun 89 22:35:54 GMT

In article <4684@psuvax1.cs.psu.edu> schwartz@shire.cs.psu.edu (Scott Schwartz) writes:
>>(Me?  I find the Pascal theory very attractive but at the moment am fully
>>in the C camp for pragmatic reasons.  Combining the virtues of the two
>>ought not to be impossible but seems to be difficult in practice.  Perhaps
>>a mixed approach is better than trying to pick one or the other.)
>
>Isn't this what Turing Plus tries to do?  

There are several languages that try to provide a "safe" subset and a more
powerful version that can be used only in "unsafe" modules.  (It's been a
long time since I read about Turing Plus, but that's my vague memory of it;
certainly this is Modula 3's approach.)  There are two problems with this.
First, restrictions on how unsafe code can be used are common (e.g. one
must call a function to get at it).  Second, the unsafe language is
seldom anywhere near as powerful as, say, C -- it's usually the safe
language with a few minimal, grudgingly-provided extensions.  Things like
pointer arithmetic, for example, are seldom directly available.  The usual
result is that it's easier to just write the unsafe parts in C and call
them.  You're going to have the function-call overhead anyway.

That is what I meant by a mixed approach (as opposed to a combination):
admit that you want two different languages, not a Dr.Jekyll/Mr.Hyde
combination, and concentrate on clean interfaces and fast interlanguage
calls.
-- 
You *can* understand sendmail, |     Henry Spencer at U of Toronto Zoology
but it's not worth it. -Collyer| uunet!attcan!utzoo!henry henry@zoo.toronto.edu