On 7 June 2012 14:33, Simonson, Lucanus J <lucanus.j.simonson@intel.com>wrote:
In a nutshell, concept-based-runtime-polymorphism/type-erasure allows you to have runtime polymorphism while preserving value semantics. The value of that win is very commonly underestimated.
So, is there a language feature that could be added to C++17 that would make implementing type erasure easier?
Standardize Steven's library as part of the STL?
Take the following base class: struct S { void f(); void g(); void h(); }; In the virtual function world, to enforce that interface, one merely has to write: struct AbstractS { virtual void f() = 0; virtual void g() = 0; virtual void h() = 0; }; and have others derive from it. If I wanted a type erased version of the equivalent callable interface, what do I have to do? If it isn't as simple as writing AbstractS above, only a small fraction of C++ developers will ever attempt it, let alone do it on a regular basis. Steven's library does a great job at covering a lot of cases, but adding custom concepts is a chore. Like lambdas, Steven is showing what is possible with a library, but I think we need a language extension to make it useable by the masses. -- Nevin ":-)" Liber <mailto:nevin@eviloverlord.com> (847) 691-1404