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Ownership Types, Views and Type Erasure · 4:27
Borrowing and Sum Types
Not every piece of code should own what it touches. We look at string_view and span, which borrow a pointer and a length without owning anything (and dangle if the owner dies first), then at the sum types: optional for a value or nothing, variant with visit for one of a fixed set of types, and any for anything at all, with every size and error measured on a real machine.
You will learn
- Explain what string_view and span hold and why they never own memory
- Recognise when a view dangles, and how clang and AddressSanitizer report it
- Use optional's has_value, value_or and value safely, and know that *opt is unchecked
- Dispatch on a variant with std::visit and an overloaded set of lambdas, and compare it with virtual calls and std::any