Prepare for release: rename to ponghero and pull in ccan.

[ponghero.git] / ccan / container_of / _info.c

diff --git a/ccan/container_of/_info.c b/ccan/container_of/_info.c
new file mode 100644 (file)
index 0000000..7705e38
--- /dev/null
+++ b/ccan/container_of/_info.c
@@ -0,0 +1,47 @@
+#include <stdio.h>
+#include <string.h>
+#include "config.h"
+
+/**
+ * container_of - routine for upcasting
+ *
+ * It is often convenient to create code where the caller registers a pointer
+ * to a generic structure and a callback.  The callback might know that the
+ * pointer points to within a larger structure, and container_of gives a
+ * convenient and fairly type-safe way of returning to the enclosing structure.
+ *
+ * This idiom is an alternative to providing a void * pointer for every
+ * callback.
+ *
+ * Example:
+ *     struct info
+ *     {
+ *             int my_stuff;
+ *             struct timer timer;
+ *     };
+ *
+ *     static void my_timer_callback(struct timer *timer)
+ *     {
+ *             struct info *info = container_of(timer, struct info, timer);
+ *             printf("my_stuff is %u\n", info->my_stuff);
+ *     }
+ *
+ *     int main()
+ *     {
+ *             struct info info = { .my_stuff = 1 };
+ *
+ *             register_timer(&info.timer);
+ *             ...
+ */
+int main(int argc, char *argv[])
+{
+       if (argc != 2)
+               return 1;
+
+       if (strcmp(argv[1], "depends") == 0) {
+               printf("check_type\n");
+               return 0;
+       }
+
+       return 1;
+}