Good question. The solution didn't make the cut for my initial release, but will be added soon. My plan is to have an (ordered- map ...) frame which encodes and decodes the keys in the given order. So for C interop, the frame would be
(ordered-map :a :int16, :b :float32) An alternative would be to just turn any vector which is alternating keys and types into an ordered-map, but that seems a bit too magical. Zach On Nov 23, 12:12 pm, Chris Perkins <chrisperkin...@gmail.com> wrote: > On Nov 23, 12:03 pm, Zach Tellman <ztell...@gmail.com> wrote: > > > > > > > > > > > When writing Calx [1], I discovered it was a huge pain to deal with > > mixed C datatypes in Java. When writing Aleph [2], I discovered the > > problem increases by a factor of ten when dealing with streams of > > bytes. In an attempt to alleviate my own pain, and hopefully help a > > few other people out, I've written Gloss, which can transform a simple > > byte-format specification into an encoder and streaming decoder. > > > A full writeup can be found athttps://github.com/ztellman/gloss/wiki. > > > A few people have already asked me how this differs from protocol > > buffers, so I'll preemptively answer that protocol buffers are a fixed > > format that cannot be used to interface with external systems. Gloss > > is less performant than protocol buffers, but is also much less picky > > about formats. > > > If anyone has any questions, I'd be happy to answer them. > > Looks very useful, Zach. Thanks. > > I have a question. > > I have only taken a quick look, so maybe I'm misunderstanding the > intent, but it's not clear to me how you would use this for sending > and receiving structured data from, say, a C program. > > Taking your example from the wiki: > > (def fr (compile-frame {:a :int16, :b :float32})) > > Let's say I want to talk to a C program that speaks in structs, like > this: > > struct Foo { short a; float b; } > > The problem is, the C program cares about order - the short comes > before the float. How does the Clojure program know what order I need > the fields in, since I have specified the format with a map; an > unordered data structure? Is there another way to specify a structure > where order of the fields matters? If so, why have two ways of doing > it? Or am I just missing something? > > Thanks, > > - Chris -- You received this message because you are subscribed to the Google Groups "Clojure" group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
