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From: shang@corp.mot.com (David L. Shang)
Subject: Re: What Should An Exception Handling Do? -- Clarification of rules
Reply-To: shang@corp.mot.com
Organization: MOTOROLA 
Date: Fri, 29 Mar 1996 15:23:21 GMT
Message-ID: <1996Mar29.152321.25943@schbbs.mot.com>
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In article <4jefbd$k33@kai.com> robison@kai.com (Arch Robison) writes:
> In article <1996Mar27.211117.5569@schbbs.mot.com> shang@corp.mot.com writes:
> >If resumption semantics were inferior, why should we bother to get
> >its "benefits" by simulating its semantics as below:
> 
> I should have qualified my statement "inferior" to "inferior in most cases".
>

When you say inferior, please be specific, otherwise you cannot
convince people.

> >What happen if we forget to inialize "retry"? Okay, we can use break, but
> >what happen if we have nested exceptions? "Goto" must be used, I guess.
> >Busy jumps around are no fun.
> >
> >What happen if we forget to set "result" to NULL under condition4?
> 
> What if I forget to increment my loop variables?  What if I use single 
> precision where I should have used double precision?  What if I misunderstood 
> the problem specification?  What if my disk drive explodes today?

A language cannot guarantee that every body using it do not
say someting wrong. But a good programming language should
help programmers make less errors.

Basic principles exsist. For example, a function that has
an output should guarantee that the code writer returns
an value in the correct type. The questions I asked belongs to
basic principles. Your disk drive explosion has nothing do to with
the principle of language design. 

> There is no such thing as a feature
> that "you do not pay for it if you do not use it."

If language makes you to have the above conclusion, the design of the
language is questionale. Futunately, C++ is not the language. And in
contrast,  "you do not pay for it if you do not use it" is the
design principle of C++.
 
> Thus many apparently useful features are deliberately left out of C++.
> Users who want the features can simulate them without burdening others.
> Besides, for some of these features, even the users who want them
> disagree about the precise semantics, so it is often better to let
> the users simulate the feature so that they can define the semantics
> they want.

So why should we have inheritance? virtual functions? We can use
C function pointers to simulate them! Simlation is always possible, even
with machine languages.

Finally, my original post is a question, to ask what should an
exception handling do. No one is attacking C++. People can always
express their different opinions. Please do not overact. We are
not talking a particular language here.

David Shang