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Ownership Types, Views and Type Erasure · 4:16
Type Erasure
How can std::function or std::any hold types they were never told about? We build the trick ourselves: a value-semantic Shape over plain Circle and Square structs, using a hidden Concept interface and a Model<T> template, clone() for copies, a small in-object buffer to avoid heap allocations, and a hand-made one-entry vtable. Then we time all of it against virtual calls and std::function on a real machine.
You will learn
- Implement type erasure with a Concept interface, a Model<T> template and a templated constructor
- Make an erased type copyable with a virtual clone()
- Explain the small buffer optimization and when std::function allocates
- Compare virtual calls, std::function, erased types and manual dispatch, and measure before trusting anyone's numbers