scottm@toast.net ("Scott Mayo") wrote in message news:<3dd08aad@news.toast.net>...
> Last I knew, this wasn't legal in C++ or C:
>
> extern void a(); //a, a function returning void
> void b() { return a(); } //b calls a() and returns void
>
> As far as I can see, supporting this is harmless, and maybe even a
> minor simplification for compilers. It's not useful when coding
> by hand, but a few times when writing code-generators I
> really wished it was available. Is there a reason this cannot be
> added to C++?

As everyone else has said, this is already part of C++.

However, I refute your statement that it is not useful when coding by
hand.  On the contrary, I think it is excellent style when writing
delegation functions to always 'return' the value of the delegatee
(err, is that correct English?), even if it is void.  This helps catch
problems if the return type is changed, and also fixes the annoying
asymmetry between returning void and returning anything else:

struct myclass
{
   int foo();
   char* bar();
   void baz();
};

struct contains_myclass
{
   myclass c;

   int foo()   { return c.foo(); }
   char* bar() { return c.bar(); }
   void baz()  { c.baz(); }         // why different notation here?
};

If the return type of myclass::baz is changed to something else, then
the above code will silently drop the return value.  If
contains_myclass::baz is written in the same style as the other
delegation functions, then the compiler will catch the bug.

Cheers,
Ian McCulloch

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Ron Natalie wrote:
>
> ""Scott Mayo"" <scottm@toast.net> wrote in message news:3dd08aad@news.toast.net...
>
> > As far as I can see, supporting this is harmless, and maybe even a
> > minor simplification for compilers. It's not useful when coding
> > by hand, but a few times when writing code-generators I
> > really wished it was available. Is there a reason this cannot be
> > added to C++?
>
> templates.

Simplifying the writing of templates is the reason why it WAS added to
C++.

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"James Kuyper" <kuyper@wizard.net> wrote in message news:3DD9030C.173D25@wizard.net...
> Ron Natalie wrote:
> >
> > ""Scott Mayo"" <scottm@toast.net> wrote in message news:3dd08aad@news.toast.net...
> >
> > > As far as I can see, supporting this is harmless, and maybe even a
> > > minor simplification for compilers. It's not useful when coding
> > > by hand, but a few times when writing code-generators I
> > > really wished it was available. Is there a reason this cannot be
> > > added to C++?
> >
> > templates.
>
> Simplifying the writing of templates is the reason why it WAS added to
> C++.

Yes, that was the point I was trying to make.   I should have been less terse.



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Last I knew, this wasn't legal in C++ or C:

extern void a(); //a, a function returning void
void b() { return a(); } //b calls a() and returns void

As far as I can see, supporting this is harmless, and maybe even a
minor simplification for compilers. It's not useful when coding
by hand, but a few times when writing code-generators I
really wished it was available. Is there a reason this cannot be
added to C++?



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In article <3dd08aad@news.toast.net>, Scott Mayo <scottm@toast.net>
writes
>Last I knew, this wasn't legal in C++ or C:
>
>extern void a(); //a, a function returning void
>void b() { return a(); } //b calls a() and returns void

It has been legal C++ for as long as the C++ Standard has existed. Of
course that does not mean that all compilers understand that :-)


--
Francis Glassborow      ACCU
64 Southfield Rd
Oxford OX4 1PA          +44(0)1865 246490
All opinions are mine and do not represent those of any organisation

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scottm@toast.net ("Scott Mayo") writes:

| Last I knew, this wasn't legal in C++ or C:
|
| extern void a(); //a, a function returning void
| void b() { return a(); } //b calls a() and returns void

You are misinformed: that is a valid construct in C++.

--
Gabriel Dos Reis,       gdr@integrable-solutions.net

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scottm@toast.net ("Scott Mayo") writes:

> Last I knew, this wasn't legal in C++ or C:
>
> extern void a(); //a, a function returning void
> void b() { return a(); } //b calls a() and returns void

Then you last checked before C++ was standardized, because you _can_ do this
in standard C++. Not all compilers let you, but not all compilers are fully
standard-conforming.

Anthony
--
Anthony Williams
Senior Software Engineer, Beran Instruments Ltd.
Remove NOSPAM when replying, for timely response.

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On Tue, 12 Nov 2002 05:10:08 +0000 (UTC), scottm@toast.net ("Scott
Mayo") wrote:

> Last I knew, this wasn't legal in C++ or C:

> extern void a(); //a, a function returning void
> void b() { return a(); } //b calls a() and returns void

> As far as I can see, supporting this is harmless, and maybe even a
> minor simplification for compilers. It's not useful when coding
> by hand, but a few times when writing code-generators I
> really wished it was available. Is there a reason this cannot be
> added to C++?

6.6.3/3 seems to be a serious deterrent.

John

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On Tue, 12 Nov 2002 05:10:08 +0000 (UTC), scottm@toast.net ("Scott
Mayo") wrote:

>Is there a reason this cannot be
>added to C++?

I suppose the only reason is that it's already there.

There is a specific rule for this in my unofficial
docs listed as 6.3.3/3 [stmt.return].

My guess is that this apparently strange extension has
been added to simplify writing template code.

Andrea

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On Tue, 12 Nov 2002 17:54:32 +0000 (UTC), jpotter@falcon.lhup.edu
(John Potter) wrote:

>6.6.3/3 seems to be a serious deterrent.

The next question seems to be: why not

   void f();
   void g();
   int main() {
     f(g());
   }

? Ok ok... put that gun away!!! Just joking... :-)

Genny.

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""Scott Mayo"" <scottm@toast.net> wrote in message news:3dd08aad@news.toast.net...

> As far as I can see, supporting this is harmless, and maybe even a
> minor simplification for compilers. It's not useful when coding
> by hand, but a few times when writing code-generators I
> really wished it was available. Is there a reason this cannot be
> added to C++?

templates.



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