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KHB: Synthesis: An Efficient Implementation of Fundamental Operating Systems ServicesKHB: Synthesis: An Efficient Implementation of Fundamental Operating Systems ServicesPosted Feb 27, 2008 21:58 UTC (Wed) by zlynx (subscriber, #2285)In reply to: KHB: Synthesis: An Efficient Implementation of Fundamental Operating Systems Services by pphaneuf Parent article: KHB: Synthesis: An Efficient Implementation of Fundamental Operating Systems Services
Your solution is not as ugly as another I've seen in C++ where the programmer used placement new to reconstruct the object with a different derived type (but the same base type) in-place. Now, that was scary.
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KHB: Synthesis: An Efficient Implementation of Fundamental Operating Systems Services Posted Feb 27, 2008 22:51 UTC (Wed) by pphaneuf (subscriber, #23480) [Link] My way is ugly. That way is insane. Still, I wish it was possible to manipulate vptrs and vtbls more in C++. Things like having two different implementations of a virtual method with the same signature inherited from two parents would make sense, for example (say, the "draw" methods you get while deriving from both Drawable and Cowboy).
KHB: Synthesis: An Efficient Implementation of Fundamental Operating Systems Services Posted Feb 28, 2008 20:59 UTC (Thu) by nix (subscriber, #2304) [Link] Insane? Oh. So, er, I should be ashamed that I did almost exactly that (via a custom allocator layered atop big mmap()ed hunks) in C about a year ago? (Well, it was more like a twisted sort of RCU: I'd construct a new instance that was a copy of the old one with a zero reference count, then changing pointers in the new instance's VMT-analogue, translating the object's data into a new representation at the same time. The old instance got reference-zapped when nobody was executing methods via those pointers anymore.) (yes, there were pressing reasons. It was a bundle of fun, as well. :) )
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