add ScopeGuard example

git-svn-id: svn://svn.code.sf.net/p/loki-lib/code/trunk@399 7ec92016-0320-0410-acc4-a06ded1c099a

test/ScopeGuard/main.cpp

@@ -0,0 +1,87 @@
+////////////////////////////////////////////////////////////////////////////////
+// The Loki Library
+// Copyright (c) 2006 Peter Kümmel
+// Permission to use, copy, modify, distribute and sell this software for any 
+//     purpose is hereby granted without fee, provided that the above copyright 
+//     notice appear in all copies and that both that copyright notice and this 
+//     permission notice appear in supporting documentation.
+// The author makes no representations about the 
+//     suitability of this software for any purpose. It is provided "as is" 
+//     without express or implied warranty.
+////////////////////////////////////////////////////////////////////////////////
+
+// $Header:
+
+
+
+#include <loki/ScopeGuard.h>
+#include <vector>
+#include <string>
+#include <iostream>
+
+struct UserDatabase
+{
+	void AddFriend(const std::string&, const std::string&)
+	{
+		throw 55;
+	}
+};
+
+class User
+{
+public:
+	User(UserDatabase* db) : pDB_(db){}
+
+	std::string GetName();
+
+    void AddFriend(User& newFriend);
+	void AddFriendGuarded(User& newFriend);
+
+	size_t countFriends();
+
+private:
+	typedef std::vector<User*> UserCont;
+    UserCont friends_;
+    UserDatabase* pDB_;
+};
+
+std::string User::GetName()
+{
+	return "A name";
+}
+
+size_t User::countFriends()
+{
+	return friends_.size();
+}
+
+void User::AddFriend(User& newFriend)
+{
+    friends_.push_back(&newFriend);
+    pDB_->AddFriend(GetName(), newFriend.GetName());
+}
+
+void User::AddFriendGuarded(User& newFriend)
+{
+    friends_.push_back(&newFriend);
+	Loki::ScopeGuard guard = Loki::MakeObjGuard(friends_, &UserCont::pop_back);
+    pDB_->AddFriend(GetName(), newFriend.GetName());
+    guard.Dismiss();
+}
+
+
+int main()
+{
+	UserDatabase db;
+
+	User u1(&db);
+	User u2(&db);
+
+	try{ u1.AddFriend(u2); }
+    catch (...){}
+	std::cout << "u1 countFriends: " << u1.countFriends() << "\n";
+
+	try{ u2.AddFriendGuarded(u1); }
+    catch (...){}
+	std::cout << "u2 countFriends: " << u2.countFriends() << "\n";
+}