Nevin Liber wrote
On 7 June 2012 14:33, Simonson, Lucanus J <lucanus.j.simonson@>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.
What if this were possible? Would this be an acceptable way to add custom concepts? BOOST_TYPE_ERASURE_CONCEPT( concept (sable) ( class S ) ( void member_body(S, f) ( void ) , void member_body(S, g) ( void ) , void member_body(S, h) ( void ) ) ) --Lorenzo -- View this message in context: http://boost.2283326.n4.nabble.com/Formal-Review-Request-TypeErasure-tp46303... Sent from the Boost - Dev mailing list archive at Nabble.com.