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A comment on A fun optimization trick from rsync. Parent comment

Re:A fun optimization trick from rsync by repsilat on Sunday October 28, 2018 @10:55PM (#18324705)
Not tooo uncommon either. It's a "reasonable" way to write generators in C (if you're masochistic Python programmer, I guess.)

Switch on the last return point at the top of the function, and make all variables that need to persist between calls `static`.

(I've written it before, and I swear I didn't invent it... Maybe it's just a short skip from Duff's Device? Still, using it to pick up before the last return instead of after is new trick for me!)

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Re:A fun optimization trick from rsync by dimatura on Monday October 29, 2018 @07:05AM (#18326435)
Yes, it's basically the idea in Duff's device. Protothreads (http://dunkels.com/adam/pt/) uses a pretty similar trick.
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Re:A fun optimization trick from rsync by repsilat on Monday October 29, 2018 @03:02PM (#18330246)
Ah, that's exactly the trick I was thinking of. I think I learned it from [1], but I'm pretty sure Protothreads predates that post. Thanks for the link!

1: https://www.chiark.greenend.org.uk/~sgtatham/coroutines.html

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Re:A fun optimization trick from rsync by fpoling on Monday October 29, 2018 @04:51AM (#18325912)
This was modeled on early Fortran where all local variables were static and it was trivial to implement persistent state machines.
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Re:A fun optimization trick from rsync by geezerjay on Monday October 29, 2018 @04:14AM (#18325777)
To my eyes it also looked like a Duff's device which kept track of the successful state.
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Re:A fun optimization trick from rsync by Piskvorrr on Monday October 29, 2018 @07:00AM (#18326416)
Yup. First thing that popped into my mind - with Duff's observation following shortly thereafter. Clever...too clever by half, IMNSHO.
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