Chien Pham (@chienpham)

Thanks for great writing, below is my understanding, pls let me know if I'm wrong 🙏 1. inline / precomputing (dispatch) - execute directly, no jump - well know info at compile time - e.g: simple struct, enum definition 2. static dispatch: - 1 jump to execute address - execute memory address is knowable at compile time 3. dynamic dispatch (virtual table / witness table dispatch) - inheritance / polymorphism (method override, protocol conforms …) - method execute address is stored in function table - 2 jumps when execute: (1) jumps to the function table, (2) access `vTable[method_name]` to get the execute access 4. message dispatch - powered by Objective-C runtime , pure swift don’t have message dispatch - using `objc_msgSend` to determine the implementation of a given `selector` , - complier search through class (NSObject subclass) hierarchy bottom up, - each class can provide the implementation at runtime using several method level: `resolveInstanceMethod`, `forwardingTargetForSelector` , `forwardInvocation` (similar for class method)