Breaking Dependencies: Type Erasure - The Implementation Details
summary
Shows two concrete ~20 line implementations for owning and non‑owning wrappers that use a templated constructor plus a nested base/model hierarchy, placement new into a fixed buffer, and a virtual clone/move for copying. Demonstrates a Small Buffer Optimization that avoids allocations and yields about a 10% speedup in the presenter’s bench (25k ops over ~2.5k random shapes), and an alternative manual virtual dispatch via function pointers that performs differently on GCC versus Clang. Practical code choices for copy/move semantics and storage policies are given.
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chapters (12)
- 0:00Type erasure introduction
- 1:55Type erasure vs inheritance
- 7:18External polymorphism basics
- 14:43Value wrapper encapsulation
- 18:15Copy operations and clone
- 27:10Performance with small buffer
- 31:06No dynamic allocations
- 38:56Buffer size via templates
- 41:45Storage policy challenges
- 43:51Lightweight virtual dispatch
- 51:18Type erasure summary
- 52:03Q&A
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