Re: using vector to encapulate a tree - non const copy constructors

From:
Ulrich Eckhardt <eckhardt@satorlaser.com>
Newsgroups:
comp.lang.c++.moderated
Date:
17 Nov 2006 07:35:43 -0500
Message-ID:
<fhg034-1sr.ln1@satorlaser.homedns.org>
terry wrote:

As Ulrich pointed out, mytree is not yet anything, and there can be no
containment of something that is a nothing.


[...]

I dont understand your comments or those of Ulrich.
The syntax

class T : public: mytemplate<T>

can be perfectly correct C++.


Yes, true. You don't need a complete type in order to use it as template
parameter.

Indeed is widely used and the only way to do certain things.


CRTP, a typical way to implement mixins.

My declaration

class mytree: public T, protected std::vector<mytree>{};

compiles perfectly on all compilers I try, and is, I think, completely
correct C++.


Yes, it might compile, but the standard requires for class vector that the
type it is constructed on be a complete type. This only means that it might
fail on a different compiler, not that it is in itself invalid C++. I
mentioned this as a warning, because it can fail, but what is true is that
it can be made to work in a similar way.

I had hoped my examples near the end of the original posting would be
clear.


Yes, the example was clear, it was just a side issue I noticed.

cheers

Uli

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