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Show HN: C library of generic, reference-counted data structures

theck01.github.io

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Re: Show HN: C library of generic, reference-counted data structures

#2

Post by andrewcooke »

nice. it's heartwarming to see things like this in c. in my spare time i am working on struct-sql mapping. it sometimes feels like the popular c libraries don't try hard enough to provide the convenience we get in other languages. with a little imagination (as here) i think we can push things a little further...

Re: Show HN: C library of generic, reference-counted data structures

#5

Post by jessedhillon »

andrewcooke wrote: post #2

nice. it's heartwarming to see things like this in c. in my spare time i am working on struct-sql mapping. it sometimes feels like the popular c libraries don't try hard enough to provide the convenience we get in other languages. with a little imagination (as here) i think we can push things a little further...

Is your project hosted somewhere? I would love to see the source for that, no matter how early/unpolished it is.

Re: Show HN: C library of generic, reference-counted data structures

#6

Post by comex »

A small observation: CoreFoundation typedefs CFTypeRef (the generic object type) to void * , rather than having obj * be a separate type as in this library. This lets you pass pointers to any CF type to functions that expect CFTypeRe without the ugly cast: it's unsafe, as you can pass a pointer to any type without the compiler complaining, but so is explicitly casting. If you're not going to go the void * route, it would be nice to provide some macro like obj(x) to safely cast only valid types to object.

Anyway, it's nice to see a portable, modern CF-like library, although of course it's too slow for some cases where code specialization is called for.

Edit: On the general subject of C data structures, in case anyone's interested, I wrote a little portable C header that provides minimal hash table functionality using macros, with a large amount of control - still generic, but totally opposite to the approach used by this library, much lower level. It's modeled after the BSD header, provides three versions (open, closed, and a higher level version), and is completely undocumented, but I'm somewhat happy with it as a proof of concept. Just throwing it out there. https://github.com/comex/cbit/blob/master/hash.h

Re: Show HN: C library of generic, reference-counted data structures

#9

Post by cmccabe »

It's nice that you made these available. You might also want to look at queue.h from BSD (see http://fxr.watson.org/fxr/source/sys/queue.h) and tree.h (http://www.freebsd.org/cgi/cvsweb.cgi/src/sys/sys/tree.h), single-file "libraries" that can generate a few different kinds of linked list and binary tree. These don't require typecasting at all, since they generate functions for your particular type. They are also intrusive data structures, meaning you control your own allocation.

With regard to OBString: don't. Really. C strings are very flexible and powerful with just what's in the standard library. You don't need charAtStringIndex, for example: you have rindex and index. You don't need splitString; you have strtok_r. You don't need findSubstring; you have strstr.

If you think you need regexes, consider fnmatch, a libc function which matches shell wildcard patterns. It's always there, it's simple, and it's fast. Or you could bring in something like PCRE. In general, if you need full regexes in a small program, it might be worth rethinking whether your program should be in C anyway.

For some reason, I don't find myself using resizable array utility code much in C. It's pretty easy to do it yourself with realloc-- that's really one of the first things they should teach people learning practical C. Perhaps a small, minimal set of macros could wrap the reallocs and make it a little bit nicer.

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