Re: technology discussion → does the world need a "new" C ?

Bart <bc@freeuk.com> writes:

On 19/08/2024 01:01, Ben Bacarisse wrote:

Bart <bc@freeuk.com> writes:
 

>

You or he would have to go into more detail, such as an actual example, to
demonstrate whatever it is that you think is wrong about passing a pointer
argument by-reference.

No one has said any such thing, so I can't see how any more detail could
help.  I suspect you've lost track of the point being made.

>
Probably, and perhaps not just me! But I'd still quite like to know exactly
what it is that is marked as 'disallowed'.

I don't know how to explain it any better.  If you really want to know,
maybe you could say what /you/ think was incorrectly marked as
disallowed so I can see how you were interpreting the table.  You
obviously had something in mind or you could not have said Tim was
wrong.

I can't unravel this.  Take, as a concrete example, C++.  You can't pass
a pointer to function that takes an array passed by reference.  You can,
of course, pass a pointer by reference, but that is neither here nor
there.

>
OK. So why do you agree with this:
>

                            C call-by-value         call-by-reference
                            ===============         =================
        (pointer argument)  F(p)                    (disallowed)

>
What is 'pointer argument' here?

I can't see what is confusing you about this.  I agree with the above
for exactly the reasons I wrote.

>
Do you mean: 'You can't pass a pointer to a function that takes an array
passed by reference'?

Yes.  As you say below, there would be a good reason not to allow that
in a C-like language with call-by reference added.

It would be wrong (and is wrong in
C++) to pass a pointer where an array reference is expected.

>
Well, putting aside pass-by-reference, that would be wrong in C too, if you
interpret 'array reference' to be a type like T(*)[], and a 'pointer' a
type like T*.

I'm not sure what this true remark adds.  Everything that is in
discussion relates to call-by-reference where that clearly does not just
mean "passing a pointer".

With pass-by-reference added to C, there would be stronger type checking,
so if something is disallowed, it would be for a good reason, not just
because Tim said so.

Or maybe, just maybe, Tim said it for good reason.

--
Ben.