ccan/ccan/tal/_info

#include <stdio.h>
#include <string.h>
#include "config.h"

/**
 * tal - compact tree allocator routines (inspired by talloc)
 *
 * Tal is a hierarchical allocator; any pointer allocated by tal can
 * become the parent of another allocation.  When you free that parent,
 * the children (and grandchildren, etc) are automatically freed.
 *
 * This allows you to build complex objects based on their lifetimes, eg:
 *
 *  struct foo *X = tal(NULL, struct foo);
 *  X->name = tal_strdup(X, "foo");
 *
 * and the pointer X->name would be a "child" of the tal context "X";
 * tal_free(X->name) would free X->name as expected, by tal_free(X) would
 * free X and X->name.
 *
 * With an overhead of approximately 2.1 pointers per object (vs. talloc's
 * 12 pointers), it's a little slower in freeing single objects, though
 * comparable for allocation and freeing whole object trees).  It does not
 * support talloc's references or failing destructors.
 *
 * Example:
 *	#include <stdio.h>
 *	#include <stdarg.h>
 *	#include <err.h>
 *	#include <ccan/talloc/talloc.h>
 *
 *	// A structure containing a popened command.
 *	struct command {
 *		FILE *f;
 *		const char *command;
 *	};
 *
 *	// When struct command is freed, we also want to pclose pipe.
 *	static void close_cmd(struct command *cmd)
 *	{
 *		pclose(cmd->f);
 *	}
 *
 *	// This function opens a writable pipe to the given command.
 *	static struct command *open_output_cmd(const tal_t *ctx,
 *					       const char *fmt, ...)
 *	{
 *		va_list ap;
 *		struct command *cmd = tal(ctx, struct command);
 *
 *		if (!cmd)
 *			return NULL;
 *
 *		va_start(ap, fmt);
 *		cmd->command = tal_vasprintf(cmd, fmt, ap);
 *		va_end(ap);
 *		if (!cmd->command) {
 *			tal_free(cmd);
 *			return NULL;
 *		}
 *
 *		cmd->f = popen(cmd->command, "w");
 *		if (!cmd->f) {
 *			tal_free(cmd);
 *			return NULL;
 *		}
 *		tal_add_destructor(cmd, close_cmd);
 *		return cmd;
 *	}
 *
 *	int main(int argc, char *argv[])
 *	{
 *		struct command *cmd;
 *
 *		if (argc != 2)
 *			errx(1, "Usage: %s <command>\n", argv[0]);
 *
 *		cmd = open_output_cmd(NULL, "%s hello", argv[1]);
 *		if (!cmd)
 *			err(1, "Running '%s hello'", argv[1]);
 *		fprintf(cmd->f, "This is a test\n");
 *		tal_free(cmd);
 *		return 0;
 *	}
 *
 * License: BSD-MIT
 */
int main(int argc, char *argv[])
{
	if (argc != 2)
		return 1;

	if (strcmp(argv[1], "depends") == 0) {
		printf("ccan/compiler\n");
		printf("ccan/hash\n");
		printf("ccan/likely\n");
		printf("ccan/list\n");
		printf("ccan/str\n");
		printf("ccan/take\n");
		printf("ccan/typesafe_cb\n");
		return 0;
	}

	return 1;
}