Callable Objects in Java, C#, Rust, and C++
summary
Compares how Java uses lambdas and a runtime method handle to adapt arbitrary method names, how C# exposes a fat pointer called a delegate, and how Rust uses retrospective implementations and trait object fat pointers to attach callability to existing types. Shows C++ additions — function_ref, a move only function type and a non type template parameter that builds a pointer‑to‑member thunk at call site — that reproduce those capabilities and actually reduce indirection and boilerplate. The library change compiles and interoperates with existing code and yields measurable ergonomic gains.
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chapters (7)
- 0:00Callable objects overview
- 8:03Java functional interfaces
- 27:19C# delegates details
- 40:07Rust traits and callables
- 53:28C++ type erasure
- 1:04:39C++23 function_ref
- 1:14:04Summary
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