From c2eeec205dbf17f6ca38fda2671c6aaf2d1c505f Mon Sep 17 00:00:00 2001
From: Mikko Rasa <tdb@tdb.fi>
Date: Wed, 25 May 2011 21:35:59 +0300
Subject: [PATCH] Make help message printing automatic Start making more use of
 std exception classes

---
 source/core/application.cpp | 39 +++++---------------------
 source/core/application.h   |  3 --
 source/core/getopt.cpp      | 56 ++++++++++++++++++++++++-------------
 source/core/getopt.h        | 24 +++++++++++++---
 4 files changed, 63 insertions(+), 59 deletions(-)

diff --git a/source/core/application.cpp b/source/core/application.cpp
index 139f94f..a60f605 100644
--- a/source/core/application.cpp
+++ b/source/core/application.cpp
@@ -8,12 +8,9 @@ Distributed under the LGPL
 #include <signal.h>
 #include <iostream>
 #include <typeinfo>
-#include "../debug/backtrace.h"
 #include "../debug/demangle.h"
-#include "../time/units.h"
-#include "../time/utils.h"
 #include "application.h"
-#include "except.h"
+#include "getopt.h"
 
 using namespace std;
 
@@ -29,7 +26,8 @@ Application::Application():
 
 /**
 Constructs an instance of the registered application class and runs it.  If the
-application throws a UsageError, the static usage() function is called.
+application throws a usage_error, a help message is printed.  The GetOpt class
+will throw such exceptions automatically in error conditions.
 
 This function can only be called once.  The global main() function provided by
 the library normally does it automatically at program startup.
@@ -58,9 +56,10 @@ int Application::run(int argc, char **argv, void *data)
 		{
 			app_ = starter_->create_app(argc, argv);
 		}
-		catch(const UsageError &e)
+		catch(const usage_error &e)
 		{
-			starter_->usage(e.what(), argv[0], e.get_brief());
+			cerr<<e.what()<<'\n';
+			cerr<<e.help()<<'\n';
 			return 1;
 		}
 
@@ -81,36 +80,12 @@ int Application::run(int argc, char **argv, void *data)
 		cerr<<"An uncaught exception occurred.\n";
 		cerr<<"  type:   "<<Debug::demangle(typeid(e).name())<<'\n';
 		cerr<<"  what(): "<<e.what()<<'\n';
-
-		const Exception *exc = dynamic_cast<const Exception *>(&e);
-		if(exc && !exc->get_backtrace().get_frames().empty())
-		{
-			cerr<<"  backtrace:\n";
-			const list<Debug::Backtrace::StackFrame> &frames = exc->get_backtrace().get_frames();
-			for(list<Debug::Backtrace::StackFrame>::const_iterator i=frames.begin(); i!=frames.end(); ++i)
-				cerr<<"    "<<*i<<'\n';
-		}
 #endif
 
 		return 124;
 	}
 }
 
-/**
-Prints a message describing the usage of the application.  The default version
-will blame the programmer for being lazy.
-
-@param   reason  Why the function was called
-@param   argv0   The value of argv[0], to be used in the message
-@param   brief   Whether to print a brief or long usage message
-*/
-void Application::usage(const char *reason, const char *, bool)
-{
-	if(reason)
-		cerr<<"UsageError: "<<reason<<'\n';
-	cerr<<"The programmer was lazy and didn't write a usage() function for this application.\n";
-}
-
 /**
 Default main loop.  Calls tick() repeatedly until exit() is called.  A custom
 main loop should monitor the done member variable and return exit_code.
@@ -153,7 +128,7 @@ void Application::sighandler_(int s)
 Application::Starter::Starter()
 {
 	if(starter_)
-		throw InvalidState("Can't create more than one Starter instance");
+		throw logic_error("Can't create more than one Starter instance");
 
 	starter_ = this;
 }
diff --git a/source/core/application.h b/source/core/application.h
index b51ac3c..4ae8c56 100644
--- a/source/core/application.h
+++ b/source/core/application.h
@@ -25,7 +25,6 @@ protected:
 		virtual ~Starter() { }
 
 		virtual Application *create_app(int, char **) = 0;
-		virtual void usage(const char *, const char *, bool) = 0;
 	};
 
 	bool done;
@@ -44,7 +43,6 @@ public:
 	virtual ~Application() { }
 
 	static int run(int, char **, void * =0);
-	static void usage(const char *, const char *, bool);
 	static void *get_data() { return data_; }
 
 protected:
@@ -66,7 +64,6 @@ private:
 	{
 	public:
 		Application *create_app(int argc, char **argv) { return new T(argc, argv); }
-		void usage(const char *r, const char *a, bool b) { T::usage(r, a, b); }
 	};
 
 	static Starter starter_;
diff --git a/source/core/getopt.cpp b/source/core/getopt.cpp
index 74f1476..9b8b84c 100644
--- a/source/core/getopt.cpp
+++ b/source/core/getopt.cpp
@@ -11,6 +11,12 @@ using namespace std;
 
 namespace Msp {
 
+GetOpt::GetOpt():
+	help(false)
+{
+	add_option("help", help, NO_ARG).set_help("Displays this help");
+}
+
 GetOpt::~GetOpt()
 {
 	for(list<OptBase *>::iterator i=opts.begin(); i!=opts.end(); ++i)
@@ -22,7 +28,7 @@ GetOpt::OptBase &GetOpt::get_option(char s)
 	for(list<OptBase *>::iterator i=opts.begin(); i!=opts.end(); ++i)
 		if((*i)->get_short()==s)
 			return **i;
-	throw UsageError(string("Unknown option -")+s);
+	throw usage_error(string("Unknown option -")+s);
 }
 
 GetOpt::OptBase &GetOpt::get_option(const string &l)
@@ -30,32 +36,42 @@ GetOpt::OptBase &GetOpt::get_option(const string &l)
 	for(list<OptBase *>::iterator i=opts.begin(); i!=opts.end(); ++i)
 		if((*i)->get_long()==l)
 			return **i;
-	throw UsageError(string("Unknown option --")+l);
+	throw usage_error(string("Unknown option --")+l);
 }
 
 void GetOpt::operator()(unsigned argc, const char *const *argv)
 {
-	unsigned i = 1;
-	for(; i<argc;)
+	try
 	{
-		if(argv[i][0]=='-')
+		unsigned i = 1;
+		for(; i<argc;)
 		{
-			if(argv[i][1]=='-')
+			if(argv[i][0]=='-')
 			{
-				if(!argv[i][2])
-					break;
-
-				i += process_long(argv+i);
+				if(argv[i][1]=='-')
+				{
+					if(!argv[i][2])
+						break;
+
+					i += process_long(argv+i);
+				}
+				else
+					i += process_short(argv+i);
 			}
 			else
-				i += process_short(argv+i);
+				args.push_back(argv[i++]);
 		}
-		else
-			args.push_back(argv[i++]);
+		
+		for(; i<argc; ++i)
+			args.push_back(argv[i]);
 	}
-	
-	for(; i<argc; ++i)
-		args.push_back(argv[i]);
+	catch(const usage_error &e)
+	{
+		throw usage_error(e.what(), "Usage: "+generate_usage(argv[0]));
+	}
+
+	if(help)
+		throw usage_error(string("Help for ")+argv[0]+":", generate_help());
 }
 
 unsigned GetOpt::process_long(const char *const *argp)
@@ -75,7 +91,7 @@ unsigned GetOpt::process_long(const char *const *argp)
 	else if(opt.get_arg_type()==REQUIRED_ARG)
 	{
 		if(!argp[1])
-			throw UsageError("Premature end of arguments");
+			throw usage_error("--"+string(arg)+" requires an argument");
 
 		// Process the next argument as option argument
 		opt.process(argp[1]);
@@ -106,7 +122,7 @@ unsigned GetOpt::process_short(const char *const *argp)
 		else if(opt.get_arg_type()==REQUIRED_ARG)
 		{
 			if(!argp[1])
-				throw UsageError("Premature end of arguments");
+				throw usage_error("-"+string(1, *arg)+" requires an argument");
 			
 			// Use the next argument as option argument
 			opt.process(argp[1]);
@@ -226,7 +242,7 @@ GetOpt::OptBase &GetOpt::OptBase::set_help(const string &h, const string &m)
 void GetOpt::OptBase::process()
 {
 	if(arg_type==REQUIRED_ARG)
-		throw UsageError("--"+lng+" requires an argument");
+		throw usage_error("--"+lng+" requires an argument");
 	++seen_count;
 
 	store();
@@ -235,7 +251,7 @@ void GetOpt::OptBase::process()
 void GetOpt::OptBase::process(const string &arg)
 {
 	if(arg_type==NO_ARG)
-		throw UsageError("--"+lng+" takes no argument");
+		throw usage_error("--"+lng+" takes no argument");
 	++seen_count;
 
 	store(arg);
diff --git a/source/core/getopt.h b/source/core/getopt.h
index 8e0f49a..d45e888 100644
--- a/source/core/getopt.h
+++ b/source/core/getopt.h
@@ -8,13 +8,27 @@ Distributed under the LGPL
 #ifndef MSP_CORE_GETOPT_H_
 #define MSP_CORE_GETOPT_H_
 
+#include <list>
 #include <sstream>
+#include <stdexcept>
 #include <string>
 #include <vector>
-#include "except.h"
 
 namespace Msp {
 
+class usage_error: public std::runtime_error
+{
+private:
+	std::string help_;
+
+public:
+	usage_error(const std::string &w, const std::string &h = std::string()): std::runtime_error(w), help_(h) { }
+	~usage_error() throw() { }
+
+	const char *help() const throw() { return help_.c_str(); }
+};
+
+
 class GetOpt
 {
 public:
@@ -69,7 +83,7 @@ private:
 			std::istringstream ss(a);
 			ss>>tmp;
 			if(ss.fail())
-				throw UsageError("Invalid argument for --"+lng);
+				throw usage_error("Invalid argument for --"+lng);
 
 			data = tmp;
 		}
@@ -82,7 +96,7 @@ private:
 	{
 	public:
 		ListOption(char s, const std::string &l, T &d, ArgType a): OptBase(s, l, a), data(d)
-		{ if(arg_type!=REQUIRED_ARG) throw Exception("ListOption with arg_type!=REQUIRED makes no sense"); }
+		{ if(arg_type!=REQUIRED_ARG) throw std::invalid_argument("ListOption arg_type!=REQUIRED"); }
 
 		virtual void store() { }
 
@@ -92,7 +106,7 @@ private:
 			std::istringstream ss(a);
 			ss>>tmp;
 			if(ss.fail())
-				throw UsageError("Invalid argument for --"+lng);
+				throw usage_error("Invalid argument for --"+lng);
 
 			data.push_back(tmp);
 		}
@@ -100,10 +114,12 @@ private:
 		T &data;
 	};
 
+	bool help;
 	std::list<OptBase *> opts;
 	std::vector<std::string> args;
 
 public:
+	GetOpt();
 	~GetOpt();
 
 	const std::vector<std::string> &get_args() const { return args; }
-- 
2.43.0