Re: Pointers explained?

[Adam Beneschan <adam@irvine.com>]

On Jul 30, 2:23 pm, Maciej Sobczak <see.my.homep...@gmail.com> wrote:
> On 30 Lip, 21:36, Adam Beneschan <a...@irvine.com> wrote:
>
> > C++ will of
> > course let you do that
>
> C++ will of course let you do that, but this statement itself is
> meaningless, because languages are never used directly. In real life
> you might want to use a *compiler* to compile the C++ code and recent
> versions of g++ produce a nice warning message when you try to return
> an address of a local variable (even without any additional options).
> I guess other C++ compilers are smart enough to do the same, so it's
> not that bad.

Please refer to the first thing I said in my response.  I guess you
proved it correct.  :)  I basically use C++ when I'm absolutely forced
to and never at any other time, so I'll take your word for it.


> On the other hand it is true that the whole scenario can be made more
> complex up to the point where the compiler will not catch the problem,
> but will have to accept it, so it's not perfect either.
>
> Note that Ada programmers also have 'Unrestricted_Access (GNAT) and
> 'Unchecked_Access to cheat around the rules.

Yes, but Ada programmers are aware of the danger and understand why
the rules are there; and they won't use 'Unchecked_Access unless it's
absolutely necessary and they know there won't be any dangling pointer
problems.

Note that "Ada programmer" is not a synonym for "programmer who uses
Ada" here.  I'm sure there are plenty of programmers who use Ada but
think like C/C++ programmers.  Those programmers would see the error
message that says 'Access is illegal because of the accessibility
rules, and figure they can solve the problem simply by changing it to
'Unchecked_Access".  Unfortunately, I've seen that sort of Ada code---
quite frustrating.

                        -- Adam