Hi Robert, Focussing on the term "concept" below. I'll comment on some of the other parts later. On 2014-08-05 17:29, Robert Ramey wrote:
I believe that "C++ Concept" was originally defined by the following web page or writing contemporary to it. https://www.sgi.com/tech/stl/stl_introduction.html . A relevent quote is
"One very important question to ask about any template function, not just about STL algorithms, is what the set of types is that may correctly be substituted for the formal template parameters. Clearly, for example, int* or double* may be substituted for find's formal template parameter InputIterator. " Thanks for providing this link!
Citing from it: "we call such a set of type requirements a /concept. [...] //We say that a type /conforms to a concept/, or that it /is a model of a concept/, if it satisfies all of those requirements"/.
I don't think we want to alter this definition. It's not formal (in the mathematical sense), but it's not ambiguous in our context.
My complaint isn't the definition - it's the phrase/word that was chosen to embody the idea. The word chosen was "Concepts" which, in my view has led to all sorts of confusion to the casual reader - as most of are when we read documentation. So my view is that we would be better served by using the term "type requirements" and/or "type constraints" rather than the word "Concepts". That's all. Of course people can and will continue to use the word "Concept" in the way they have been. But that doesn't prohibit me from using the phrase "type constraint" from referring to the original idea.
Calling it "type requirements" would be fully backed by the SGI document. [...]
But with C++11 it's much more interesting. I just came upon:
http://en.cppreference.com/w/cpp/concept First sentence: "A concept is a term that describes a *named set of requirements* for a type"
which echoes my views on the whole subject. I don't have the C++11 spec - but I'm assuming/hoping that these type requirements are part of it. This section only defines the named type requirements.
Cheers, Roland