C++ Zero Overhead Pass by Value Through Invocable C++ Abstractions
summary
Library type erasure like std::function currently forces an extra copy/move when a non‑trivial object is passed by value; the claim is that this can be avoided. The technique rewrites the callee pointer types at runtime using a reinterpret_cast thunk that replaces non‑trivial value parameters with rvalue references (relying on the Itanium ABI calling convention), adds a constrained constructor and a match_signature overload resolution trick to pick the correct call operator, and yields a function_ref style abstraction that eliminates the extra copy/move on tested platforms (works but is formally undefined behavior).
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chapters (8)
- 0:00Introduction and motivation
- 2:30Passing values through abstractions
- 9:12Implementing function_ref
- 12:05Motivation and performance
- 17:50Constructors for free functions
- 18:12Member functions support
- 22:45Function objects and overloads
- 34:26Q&A and conclusion
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