WeakPtr: weak-pointer design, learned from Chromium

This directory implements a Chromium-style WeakPtr component and works through the modern C++ design of observing whether an object is still alive, without taking ownership. It sits alongside the OnceCallback series — the industrial-strength answer to the hand-rolled cancellation token from 01-4 is WeakPtr.

Full tutorial (full/)

For readers starting fresh, from weak-reference concepts and prerequisites through to a complete implementation.

Prerequisites (7 chapters):

• weak references and the lifetime puzzle
• intrusive refcounting and scoped_refptr
• std::atomic and memory_order
• sequences, SEQUENCE_CHECKER, and DCHECK/CHECK
• concepts and requires, advanced
• template friends and uintptr_t type erasure
• TRIVIAL_ABI and trivial relocatability

Hands-on (6 chapters):

• motivation and API design
• core skeleton and the control block
• WeakPtrFactory and the last-member idiom
• sequence affinity and lazy binding
• callback integration — closing OnceCallback's loop
• testing and performance

Hands-on design guide (hands_on/)

For readers comfortable with C++ templates and concurrency, a quick walkthrough of the design motivation, implementation, and testing:

• motivation, API, and the control block
• step-by-step implementation
• test strategy and performance