[base] introduce a command type that gets registered with the app

base/application.cc

@@ -1,14 +1,47 @@
 #include "base/application.h"
 
+#include <boost/lexical_cast.hpp>
 #include <libgen.h>
 #include <linux/limits.h>
 #include <string.h>
+#include <stdlib.h>
 
 using namespace base;
+using namespace boost;
 using namespace std;
 
 //----------------------------------------------------------------
 
+command::command(string const &name)
+	: name_(name) {
+}
+
+void
+command::die(string const &msg)
+{
+	cerr << msg << endl;
+	usage(cerr);
+	exit(1);
+}
+
+uint64_t
+command::parse_uint64(string const &str, string const &desc)
+{
+	try {
+		// FIXME: check trailing garbage is handled
+		return lexical_cast<uint64_t>(str);
+
+	} catch (...) {
+		ostringstream out;
+		out << "Couldn't parse " << desc << ": '" << str << "'";
+		die(out.str());
+	}
+
+	return 0; // never get here
+}
+
+//----------------------------------------------------------------
+
 int
 application::run(int argc, char **argv)
 {
@@ -26,7 +59,7 @@ application::run(int argc, char **argv)
 		cmd = argv[0];
 	}
 
-	std::list<command const *>::const_iterator it;
+	std::list<command::ptr>::const_iterator it;
 	for (it = cmds_.begin(); it != cmds_.end(); ++it) {
 		if (cmd == (*it)->get_name())
 			return (*it)->run(argc, argv);
@@ -43,7 +76,7 @@ application::usage()
 	std::cerr << "Usage: <command> <args>\n"
 		  << "commands:\n";
 
-	std::list<command const *>::const_iterator it;
+	std::list<command::ptr>::const_iterator it;
 	for (it = cmds_.begin(); it != cmds_.end(); ++it) {
 		std::cerr << "  " << (*it)->get_name() << "\n";
 	}

base/application.h

@@ -1,40 +1,60 @@
 #ifndef BASE_APPLICATION_H
 #define BASE_APPLICATION_H
 
+#include <boost/shared_ptr.hpp>
 #include <iostream>
 #include <list>
 #include <string>
 #include <stdexcept>
+#include <stdint.h>
 
 //----------------------------------------------------------------
 
 namespace base {
 	class command {
 	public:
-		typedef int (*cmd_fn)(int, char **);
+		typedef boost::shared_ptr<command> ptr;
 
-		command(std::string const &name, cmd_fn fn)
-			: name_(name),
-			  fn_(fn) {
-		}
+		command(std::string const &name);
+		virtual ~command() {}
+
+		void die(std::string const &msg);
+		uint64_t parse_uint64(std::string const &str, std::string const &desc);
+
+
+		virtual void usage(std::ostream &out) const = 0;
+		virtual int run(int argc, char **argv) = 0;
 
 		std::string const &get_name() const {
 			return name_;
 		}
 
+	private:
+		std::string name_;
+
+	};
+
+	class command_old : public command {
+	public:
+		typedef int (*cmd_fn)(int, char **);
+
+		command_old(std::string const &name, cmd_fn fn)
+			: command(name),
+			  fn_(fn) {
+		}
+
 		int run(int argc, char **argv) const {
 			return fn_(argc, argv);
 		}
 
 	private:
-		std::string name_;
 		cmd_fn fn_;
 	};
 
 	class application {
 	public:
-		void add_cmd(command const &c) {
-			cmds_.push_back(&c);
+		void add_cmd(command::ptr c) {
+			cmds_.push_back(c);
 		}
 
 		int run(int argc, char **argv);
@@ -43,7 +63,7 @@ namespace base {
 		void usage();
 		std::string get_basename(std::string const &path) const;
 
-		std::list<command const *> cmds_;
+		std::list<command::ptr> cmds_;
 	};
 }