Re: Future of C++

From:

Andrei Alexandrescu <SeeWebsiteForEmail@erdani.org>

Newsgroups:

comp.lang.c++.moderated

Date:

Tue, 12 Aug 2008 10:08:26 CST

Message-ID:

<K5Gn5L.1AqE@beaver.cs.washington.edu>

Francis Glassborow wrote:

Eugene Gershnik wrote:

On Aug 9, 11:07 pm, Razvan Cojocaru <razva...@gmx.net> wrote:

[snipping heavily]

C. it's very probable that, at least at some point in time, someone will
put one of these derived class objects on the heap, and use it through a
base class pointer. Hence, we need to worry about the destructors, and
the only and best way for a destructor to be in this case, is virtual.

It was repeatedly explained to you the base class interface doesn't
have to include destructor at all. If you don't ever use this approach
- fine, but don't claim that what you do is universal principle of OO.

http://www.research.att.com/~bs/C++0x_panel.pdf

This argument is nothing but an "appeal to authority". The slides
provide no context or discussion about the issue.

Alas, it was simply an appeal to reason. I had hoped that you would at
least take a well respected expert's opinion on the issue less
lightly [...]

You didn't link any opinion, just some "on the margin" notes from some
presentation, not even a stand-alone text. It might very well be that
the author has excellent arguments for your case but you haven't shown
any. Without them it is just that: an appeal to authority.

And Bjarne Stroustrup is a highly active member of WG21 and certainly
raised this issue. So the fact that it has not been added to the draft
for C++0x would imply (correctly as it happens) that the gains did not
justify a change.

What WG21 has done is make it easier to add a virtual dtor to a base class:

class base {
public:
virtual ~base() = default;
....
};

I guess "{}" is shorter than "= default" :o). But maybe you are
referring to a shortcut for this:

class base {
public:
    virtual ~base() = 0;
.....
};

inline base::~base() {}

Is that correct?

Andrei

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