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Re: [isocpp-ext] namespace composition

From: Peter Sommerlad (C++) <"Peter>
Date: Mon, 1 May 2023 11:56:18 +0200
Hi Bjarne,

I am late on this thread, but I teach C++ in a way, where indexing is
(almost) never used, at least not for beginners. So I never felt the
need to ask for range checking (iterator invalidation is another
unfortunately related topic).

I teach beginners (who know other programming languages a bit, such as
Java or Python) an algorithm-first approach, similar (but now much
easier thanks to generic lambdas) as Barbara Moo and Andrew Koenig in
"Accelerated C++".

Using a decent IDE (which I unfortunately no longer can maintain:
Cevelop) with some student-oriented static analysis checks also helped a

Also using namespace std never was a real problem, especially after we
implemented namespace- and qualified name- related refactorings.

I understand this might not help your situation, but at least I found my


Bjarne Stroustrup via Ext wrote on 28.04.23 21:12:
> This question is in the context of teaching novices. For experienced
> programmers, I have workarounds.
> I would like to make all of the standard library available
> as a module based on module std
> with guaranteed range checking
> without requiring students to write std:: all the time
> and add a few supporting features
> I have successfully done that for tens of thousands of students over
> more than a decade using some disgusting macro tricks. Think
> #define vector My_checked_vector
> Having guaranteed range checking is a great help to students. I estimate
> that it eliminates more than 50% of crashes and lots of frustration.
> Modules and disgusting macro tricks don't go well together
> I was planning to use
> using vector = My_checked_vector
> but I can't find a way for that to work together with
> using namespace std;
> Am I being blind?
> Any suggestions?
> I can get away with a single #using "PPP_support.h" containing three
> macros, but I would really like to avoid that.
> I suspect the fundamental problem is that there is no way of composing a
> module or a namespace saying "I want all of Foo, except that I want my
> own versions of Foo::X and Foo:Y." I would *love* to be proven wrong
> about that. The original namespace design had such a mechanism, but I
> have not been able to get it to work.
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Peter Sommerlad
Better Software: Consulting, Training, Reviews
Modern, Safe & Agile C++
+41 79 432 23 32

Received on 2023-05-01 09:56:21