- * This determines if we are debugging the current connection: if so,
- * it immediately applies the plan and calls back into io_loop() to
- * create a linear call chain.
+ * This is how an io helper gets scratch space to store into; you must call
+ * io_set_plan() when you've initialized it.
+ *
+ * Example:
+ * #include <ccan/io/io_plan.h>
+ *
+ * // Simple helper to read a single char.
+ * static int do_readchar(int fd, struct io_plan_arg *arg)
+ * {
+ * return read(fd, arg->u1.cp, 1) <= 0 ? -1 : 1;
+ * }
+ *
+ * static struct io_plan *io_read_char_(struct io_conn *conn, char *in,
+ * struct io_plan *(*next)(struct io_conn*,void*),
+ * void *next_arg)
+ * {
+ * struct io_plan_arg *arg = io_plan_arg(conn, IO_IN);
+ *
+ * // Store information we need in the plan unions u1 and u2.
+ * arg->u1.cp = in;
+ *
+ * return io_set_plan(conn, IO_IN, do_readchar, next, next_arg);
+ * }