The idea behind packedobjects is to be able to use an abstract syntax for describing what gets bit packed into messages to be sent across a network. The syntax is loosely based on ASN.1 but uses s-expressions to avoid the need for an ASN.1 compiler. The encoding is based on unaligned Packed Encoding Rules (PER). So if you are looking at packing data into messages in a machine independent way it might be useful.
Cheers, John. On 16/04/2008, Martin DeMello <[EMAIL PROTECTED]> wrote: > Interesting post on one of the advantages of C++ - I just wondered how > such problems are handled in the scheme world > > > ------------------------------------------------------------------------------------------------------ > What you can do in C++ that you *can't* do in Java is define a class > whose in-memory representation maps directly to the format of data in > memory, and then say "I want to treat this large swath of memory as if > it were an array of Foo objects" - and gain all of the abstraction of > calling object methods on that data, with zero performance penalty for > instantiating thousands of objects. > > It's not something you want to do every day, but on the rare occasion > you need it, C++ comes closest to letting you have your cake and eat > it too. > > -- Avdi Grimm on the pragmaticprogrammers mailing list > > ------------------------------------------------------------------------------------------------------ > > I ran into this exact problem when trying to access a packed C data > structure from OCaml - I had to write a bunch of code to index into > the block, pull out a chunk of bytes and then write accessor functions > to do bitshifting and bitmasking to retrieve the individual members > from the struct, without much "higher level" help from OCaml. I'm > imagining some combination of C and chicken would do a nicer job of > this, and naturally I'd want to do it with as little C as possible. I > found http://chicken.wiki.br/packedobjects but I couldn't tell if it > could work directly with a block of memory or it there'd be a lot of > from/to overhead. > > martin > > > _______________________________________________ > Chicken-users mailing list > [email protected] > http://lists.nongnu.org/mailman/listinfo/chicken-users > _______________________________________________ Chicken-users mailing list [email protected] http://lists.nongnu.org/mailman/listinfo/chicken-users
