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Tuesday, September 26 • 2:00pm - 3:00pm
dynamic_cast From Scratch

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This session will introduce you to the C++ object model: the rules by which C++ class objects are translated into memory layouts. We'll quickly cover polymorphic class types and multiple and virtual inheritance. We'll discuss the anatomy of a virtual method call, the difference between `static_cast` and `reinterpret_cast`, and what's contained in a vtable besides function pointers. We'll see that the way `dynamic_cast` thinks about the class hierarchy is slightly different from the way we're used to drawing it; and that `dynamic_cast` is expensive enough that sometimes we can find cheaper ways to ask an object for its type! The climax will be a complete, bug-free, and fast implementation of C++'s built-in `dynamic_cast`, using our own hand-crafted artisanal run-time type information (RTTI).

Attendees will incidentally be exposed to several features of the modern C++ language, including type traits and the `final` qualifier.

This session will mostly be talking about the Itanium C++ ABI, which is the standard on Linux and OS X systems. Mapping these concepts to the MSVC ABI will be left as an exercise for the reader of the project's GitHub repo: https://github.com/Quuxplusone/from-scratch/tree/master/dynamic-cast#dynamic_cast-from-scratch

Speakers
avatar for Arthur O'Dwyer

Arthur O'Dwyer

Core Engineering, Nominum
Arthur O'Dwyer worked for many years at Green Hills Software, making the world's most optimizing C and C++ compilers. Now he works at Nominum in San Francisco. Arthur is the showrunner of the Bay Area C++ meetup, which meets practically every week these days.


Tuesday September 26, 2017 2:00pm - 3:00pm
Harvard (406) Meydenbauer Center

Attendees (124)