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hello_world.cpp</title>
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<span class=comment>// file : Example/ExH/HelloWorld/hello_world.cpp
// author : Boris Kolpackov <boris@kolpackov.net>
// copyright : Copyright (c) 2002-2003 Boris Kolpackov
// license : http://kolpackov.net/license.html
</span><span class=preprocessor>#include <cstdlib> // for std::abort ()
</span><span class=preprocessor>#include <string>
</span><span class=preprocessor>#include <iostream>
</span><span class=preprocessor>#include "Utility/ExH/System/Exception.hpp"
</span><span class=preprocessor>#include "Utility/ExH/Logic/Exception.hpp"
</span><span class=keyword>using </span><span class=identifier>std</span><span class=special>::</span><span class=identifier>cerr</span><span class=special>;
</span><span class=keyword>using </span><span class=identifier>std</span><span class=special>::</span><span class=identifier>cout</span><span class=special>;
</span><span class=keyword>using </span><span class=identifier>std</span><span class=special>::</span><span class=identifier>endl</span><span class=special>;
</span><span class=keyword>using </span><span class=keyword>namespace </span><span class=identifier>Utility</span><span class=special>;
</span><span class=keyword>class </span><span class=identifier>Application
</span><span class=special>{
</span><span class=keyword>public</span><span class=special>:
</span><span class=keyword>class </span><span class=identifier>Exception </span><span class=special>: </span><span class=keyword>public </span><span class=identifier>ExH</span><span class=special>::</span><span class=identifier>Logic</span><span class=special>::</span><span class=identifier>Exception </span><span class=special>{};
</span><span class=comment>// Hint: you may want to try again...
</span><span class=keyword>class </span><span class=identifier>FeelingDizzy </span><span class=special>: </span><span class=keyword>public </span><span class=identifier>Exception </span><span class=special>{};
</span><span class=keyword>class </span><span class=identifier>InvalidArg </span><span class=special>: </span><span class=keyword>public </span><span class=identifier>Exception </span><span class=special>{};
</span><span class=keyword>public</span><span class=special>:
</span><span class=identifier>Application </span><span class=special>() </span><span class=keyword>throw </span><span class=special>(</span><span class=identifier>ExH</span><span class=special>::</span><span class=identifier>System</span><span class=special>::</span><span class=identifier>Exception</span><span class=special>)
</span><span class=special>: </span><span class=comment>// The std::string c-tor may throw any kind of exceptions besides
// quite possible std::bad_alloc.
</span><span class=identifier>greeting_ </span><span class=special>(</span><span class=string>"Hello, world!"</span><span class=special>)
</span><span class=special>{
</span><span class=special>}
</span><span class=identifier>Application </span><span class=special>(</span><span class=keyword>char </span><span class=keyword>const </span><span class=special>* </span><span class=identifier>greeting</span><span class=special>) </span><span class=keyword>throw </span><span class=special>(</span><span class=identifier>InvalidArg</span><span class=special>,
</span><span class=identifier>ExH</span><span class=special>::</span><span class=identifier>System</span><span class=special>::</span><span class=identifier>Exception</span><span class=special>)
</span><span class=special>: </span><span class=identifier>greeting_ </span><span class=special>(</span><span class=identifier>greeting </span><span class=special>== </span><span class=number>0 </span><span class=special>? </span><span class=string>"" </span><span class=special>: </span><span class=identifier>greeting</span><span class=special>)
</span><span class=special>{
</span><span class=keyword>if </span><span class=special>(</span><span class=identifier>greeting </span><span class=special>== </span><span class=number>0</span><span class=special>) </span><span class=keyword>throw </span><span class=identifier>InvalidArg </span><span class=special>();
</span><span class=special>}
</span><span class=keyword>public</span><span class=special>:
</span><span class=keyword>void
</span><span class=identifier>run </span><span class=special>() </span><span class=keyword>throw </span><span class=special>(</span><span class=identifier>FeelingDizzy</span><span class=special>, </span><span class=identifier>ExH</span><span class=special>::</span><span class=identifier>System</span><span class=special>::</span><span class=identifier>Exception</span><span class=special>)
</span><span class=special>{
</span><span class=keyword>static </span><span class=keyword>unsigned </span><span class=keyword>int </span><span class=identifier>dizzy_count </span><span class=special>(</span><span class=number>0</span><span class=special>);
</span><span class=keyword>if </span><span class=special>(</span><span class=identifier>dizzy_count</span><span class=special>++ </span><span class=special>< </span><span class=number>5</span><span class=special>) </span><span class=keyword>throw </span><span class=identifier>FeelingDizzy </span><span class=special>();
</span><span class=comment>// The next line can throw full bucket of exceptions
// not to mention ios_base::failure.
</span><span class=identifier>cout </span><span class=special><< </span><span class=identifier>greeting_</span><span class=special>.</span><span class=identifier>c_str </span><span class=special>() </span><span class=special><< </span><span class=identifier>endl</span><span class=special>;
</span><span class=special>}
</span><span class=keyword>private</span><span class=special>:
</span><span class=identifier>std</span><span class=special>::</span><span class=identifier>string </span><span class=identifier>greeting_</span><span class=special>;
</span><span class=special>};
</span><span class=keyword>int
</span><span class=identifier>main </span><span class=special>()
</span><span class=special>{
</span><span class=comment>// This is a catch-all layer that should be in use only
// if we are really in trouble.
</span><span class=keyword>try
</span><span class=special>{
</span><span class=comment>// This is a catch-system layer. Here we will catch exceptions like
// bad_alloc, etc. If we get here it means that nobody wanted/managed
// to recover from this kind of errors.
</span><span class=keyword>try
</span><span class=special>{
</span><span class=comment>// This is a catch-logic layer. If we get here it usually
// indicates an application logic error.
</span><span class=keyword>try
</span><span class=special>{
</span><span class=comment>// Ok, here we go about our application logic.
</span><span class=keyword>try
</span><span class=special>{
</span><span class=keyword>for </span><span class=special>(</span><span class=keyword>int </span><span class=identifier>i </span><span class=special>= </span><span class=number>0</span><span class=special>; </span><span class=identifier>i </span><span class=special>< </span><span class=number>10</span><span class=special>; </span><span class=identifier>i</span><span class=special>++)
</span><span class=special>{
</span><span class=keyword>try
</span><span class=special>{
</span><span class=identifier>Application </span><span class=identifier>app </span><span class=special>(</span><span class=string>"Hi dude!"</span><span class=special>);
</span><span class=identifier>app</span><span class=special>.</span><span class=identifier>run </span><span class=special>();
</span><span class=keyword>break</span><span class=special>;
</span><span class=special>}
</span><span class=keyword>catch </span><span class=special>(</span><span class=identifier>Application</span><span class=special>::</span><span class=identifier>FeelingDizzy </span><span class=keyword>const</span><span class=special>& </span><span class=special>)
</span><span class=special>{
</span><span class=keyword>if </span><span class=special>(</span><span class=identifier>i </span><span class=special>== </span><span class=number>9</span><span class=special>)
</span><span class=special>{
</span><span class=identifier>cerr </span><span class=special><< </span><span class=string>"Given up!" </span><span class=special><< </span><span class=identifier>endl</span><span class=special>;
</span><span class=keyword>return </span><span class=special>-</span><span class=number>1</span><span class=special>;
</span><span class=special>}
</span><span class=keyword>else
</span><span class=special>{
</span><span class=identifier>cerr </span><span class=special><< </span><span class=string>"Application is feeling dizzy. Trying again..."
</span><span class=special><< </span><span class=identifier>endl</span><span class=special>;
</span><span class=special>}
</span><span class=special>}
</span><span class=special>}
</span><span class=special>}
</span><span class=keyword>catch </span><span class=special>(</span><span class=identifier>Application</span><span class=special>::</span><span class=identifier>InvalidArg </span><span class=keyword>const</span><span class=special>& </span><span class=special>)
</span><span class=special>{
</span><span class=identifier>cerr </span><span class=special><< </span><span class=string>"Cought Application::InvalidArg : ...hmm... strange!"
</span><span class=special><< </span><span class=identifier>endl</span><span class=special>;
</span><span class=keyword>return </span><span class=special>-</span><span class=number>1</span><span class=special>;
</span><span class=special>}
</span><span class=special>}
</span><span class=keyword>catch </span><span class=special>(</span><span class=identifier>ExH</span><span class=special>::</span><span class=identifier>Logic</span><span class=special>::</span><span class=identifier>Exception </span><span class=keyword>const</span><span class=special>& </span><span class=identifier>e</span><span class=special>)
</span><span class=special>{
</span><span class=identifier>cerr </span><span class=special><< </span><span class=string>"Caught Logic::Exception : " </span><span class=special><< </span><span class=identifier>e</span><span class=special>.</span><span class=identifier>what </span><span class=special>() </span><span class=special><< </span><span class=identifier>endl</span><span class=special>;
</span><span class=keyword>return </span><span class=special>-</span><span class=number>1</span><span class=special>;
</span><span class=special>}
</span><span class=special>}
</span><span class=keyword>catch </span><span class=special>(</span><span class=keyword>const </span><span class=identifier>ExH</span><span class=special>::</span><span class=identifier>System</span><span class=special>::</span><span class=identifier>Exception</span><span class=special>& </span><span class=identifier>e</span><span class=special>)
</span><span class=special>{
</span><span class=identifier>cerr </span><span class=special><< </span><span class=string>"Caught System::Exception : " </span><span class=special><< </span><span class=identifier>e</span><span class=special>.</span><span class=identifier>what </span><span class=special>() </span><span class=special><< </span><span class=identifier>endl</span><span class=special>;
</span><span class=keyword>return </span><span class=special>-</span><span class=number>1</span><span class=special>;
</span><span class=special>}
</span><span class=keyword>catch </span><span class=special>(...)
</span><span class=special>{
</span><span class=identifier>cerr </span><span class=special><< </span><span class=string>"Caught unknown exception using catch-all handler. " </span><span class=special><< </span><span class=identifier>endl</span><span class=special>;
</span><span class=keyword>return </span><span class=special>-</span><span class=number>1</span><span class=special>;
</span><span class=special>}
</span><span class=special>}
</span><span class=keyword>catch </span><span class=special>(...)
</span><span class=special>{
</span><span class=comment>// We get here in cases of some hard failure. For example when handling
// exception, operator << throws another exception. Usually application
// cannot handle such failures itself so we just propagate it futher.
</span><span class=identifier>std</span><span class=special>::</span><span class=identifier>abort </span><span class=special>();
</span><span class=special>}
</span><span class=special>}
</span></pre>
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