X-Git-Url: https://git.ozlabs.org/?p=ccan;a=blobdiff_plain;f=ccan%2Ftypesafe_cb%2F_info;h=2d8f68483a5b333ac086fa6d87a42e4debe0c57c;hp=5e35eb7652ece2a30b2d64118de5e9a790cb8c57;hb=f4b1f445a7b21b1599530afb897ef54efe15479d;hpb=570c9c555f076e74f46141bb42b5d1d7ac89f632

diff --git a/ccan/typesafe_cb/_info b/ccan/typesafe_cb/_info
index 5e35eb76..2d8f6848 100644
--- a/ccan/typesafe_cb/_info
+++ b/ccan/typesafe_cb/_info
@@ -46,7 +46,95 @@
  * cast_if_type() and friend become an unconditional cast, so your
  * code will compile but you won't get type checking.
  *
+ * Example:
+ *	#include <ccan/typesafe_cb/typesafe_cb.h>
+ *	#include <stdlib.h>
+ *	#include <stdio.h>
+ *
+ *	// Generic callback infrastructure.
+ *	struct callback {
+ *		struct callback *next;
+ *		int value;
+ *		int (*callback)(int value, void *arg);
+ *		void *arg;
+ *	};
+ *	static struct callback *callbacks;
+ *	
+ *	static void _register_callback(int value, int (*cb)(int, void *),
+ *				       void *arg)
+ *	{
+ *		struct callback *new = malloc(sizeof(*new));
+ *		new->next = callbacks;
+ *		new->value = value;
+ *		new->callback = cb;
+ *		new->arg = arg;
+ *		callbacks = new;
+ *	}
+ *	#define register_callback(value, cb, arg)			\
+ *		_register_callback(value,				\
+ *				   typesafe_cb_preargs(int, (cb), (arg), int),\
+ *				   (arg))
+ *	
+ *	static struct callback *find_callback(int value)
+ *	{
+ *		struct callback *i;
+ *	
+ *		for (i = callbacks; i; i = i->next)
+ *			if (i->value == value)
+ *				return i;
+ *		return NULL;
+ *	}   
+ *
+ *	// Define several silly callbacks.  Note they don't use void *!
+ *	#define DEF_CALLBACK(name, op)			\
+ *		static int name(int val, const int *arg)\
+ *		{					\
+ *			printf("%s", #op);		\
+ *			return val op *arg;		\
+ *		}
+ *	DEF_CALLBACK(multiply, *);
+ *	DEF_CALLBACK(add, +);
+ *	DEF_CALLBACK(divide, /);
+ *	DEF_CALLBACK(sub, -);
+ *	DEF_CALLBACK(or, |);
+ *	DEF_CALLBACK(and, &);
+ *	DEF_CALLBACK(xor, ^);
+ *	DEF_CALLBACK(assign, =);
+ *
+ *	// Silly game to find the longest chain of values.
+ *	int main(int argc, char *argv[])
+ *	{
+ *		int i, run = 1, num = argv[1] ? atoi(argv[1]) : 0;
+ *	
+ *		for (i = 1; i < 1024;) {
+ *			// Since run is an int, compiler checks "add" does too.
+ *			register_callback(i++, add, &run);
+ *			register_callback(i++, divide, &run);
+ *			register_callback(i++, sub, &run);
+ *			register_callback(i++, multiply, &run);
+ *			register_callback(i++, or, &run);
+ *			register_callback(i++, and, &run);
+ *			register_callback(i++, xor, &run);
+ *			register_callback(i++, assign, &run);
+ *		}
+ *	
+ *		printf("%i ", num);
+ *		while (run < 56) {
+ *			struct callback *cb = find_callback(num % i);
+ *			if (!cb) {
+ *				printf("-> STOP\n");
+ *				return 1;
+ *			}
+ *			num = cb->callback(num, cb->arg);
+ *			printf("->%i ", num);
+ *			run++;
+ *		}
+ *		printf("-> Winner!\n");
+ *		return 0;
+ *	}
+ *
  * Licence: LGPL (2 or any later version)
+ * Author: Rusty Russell <rusty@rustcorp.com.au>
  */
 int main(int argc, char *argv[])
 {