oboe/osx/dialogxml/xml-parser/tutorial_ticpp.txt

/**
@page ticppTutorial TinyXML++ Tutorial
Take a look here @subpage ticpp

This is a work in progress.


@page ticpp TinyXML++
<h2> General Concepts </h2>
The TinyXML++ classes are all wrappers around the corresponding classes within TinyXML.

There is no reason to create TinyXML++ objects on the heap, using @p new, because the memory is managed for you. If you choose
to use @p new to create TinyXML++ objects, you will @b always need to use @p delete to clean up.

Basically, TinyXML++ objects are just wrappers around TinyXML pointers.

<h2> Goals </h2>
- Simplify the use and interface of TinyXml, using C++ concepts.
	- Use exceptions for error handling, so there are no return codes to check
	- Use templates for automatic type conversion
	- Use STL style iterators to move through nodes and attributes

<h2> Details </h2>
<h3> Use exceptions for error handling </h3>
When using the original TinyXML, every function returns a value indicating
success or failure. A programmer would have to check that value to ensure
the function succeeded.

Example:
@code
// Load a document
TiXmlDocument doc( pFilename );
if ( !doc.LoadFile() ) return;

// Get a node
TiXmlElement* pElem = doc.FirstChildElement();
if ( !pElem ) return;

// Get the node we want
pElem = pElem->NextSibling();
if ( !pElem ) return;

// do something useful here
@endcode

An alternative was to use TiXmlHandle, which allows for function chaining by
checking the intermediate function return values:

Example:
@code
// Load a document
TiXmlDocument doc(pFilename);
if (!doc.LoadFile()) return;

// Make a document handle
TiXmlHandle hDoc(&doc);

// Get an element by using the handle to chain calls
// Note the conversion of the TiXmlHandle to the TiXmlElement* - .Element()
TiXmlElement* pElem = hDoc.FirstChildElement().NextSibling().Element();
if ( !pElem ) return;

// do something useful here
@endcode

With TinyXML++, if there is an error during a function call, it throws an exception.
This means that a programmer can assume that every function is successful, as
long as the functions are enclosed in a try-catch block.

Example:
@code
try
{
	// Load a document
	ticpp::Document doc( pFilename );
	doc.LoadFile();

	// Get an element by chaining calls - no return values to check, no TiXmlHandle
	ticpp::Element* pElem = doc.FirstChildElement()->NextSibling();

	// do something useful here
}
catch( ticpp::Exception& ex )
{
	// If any function has an error, execution will enter here.
	// Report the error
	std::cout << ex.what();
}
@endcode


<h3> Use templates for automatic type conversion </h3>
When using TinyXML, a programmer either needs to convert values to and from
strings, or choose from one of many overloads to get the value in the desired
type.

Example:
@code
// Load a document
TiXmlDocument doc( pFilename );
if ( !doc.LoadFile() ) return;

// Get a node
TiXmlElement* pElem = doc.FirstChildElement();
if ( !pElem ) return;

// Get the node we want
pElem = pElem->NextSibling();
if ( !pElem ) return;

// Get the attribute as a string, convert to int
const char* pszAttr = pElem->Attribute( "myAttribute" );
int attr = atoi( pszAttr );

// Get the attribute as an int
int attr2;
if ( TIXML_SUCCESS != pElem->QueryIntAttribute( "myAttribute", &attr2 ) )
{
	return;
}

// Get the attribute as a double
double attr3;
if ( TIXML_SUCCESS != pElem->QueryDoubleAttribute( "myAttribute", &attr3 ) )
{
	return;
}

// Get the attribute as a float
float attr4;
if ( TIXML_SUCCESS != pElem->QueryFloatAttribute( "myAttribute", &attr4 ) )
{
	return;
}
@endcode

TinyXML++ uses templates for automatic type conversion.

Example:
@code
try
{
	// Load a document
	ticpp::Document doc( pFilename );
	doc.LoadFile();

	// Get an element by chaining calls - no return values to check, no TiXmlHandle
	ticpp::Element* pElem = doc.FirstChildElement()->NextSibling();

	// GetAttribute can determine the type of the pointer, and convert automatically

	// Get the attribute as a string
	std::string attr;
	pElem->GetAttribute( "myAttribute", &attr );

	// Get the attribute as an int
	int attr2;
	pElem->GetAttribute( "myAttribute", &attr2 );

	// Get the attribute as an float
	float attr3;
	pElem->GetAttribute( "myAttribute", &attr3 );

	// Get the attribute as an double
	double attr4;
	pElem->GetAttribute( "myAttribute", &attr4 );

	// Get the attribute as an bool
	bool attr5;
	pElem->GetAttribute( "myAttribute", &attr5 );

}
catch( ticpp::Exception& ex )
{
	// If any function has an error, execution will enter here.
	// Report the error
	std::cout << ex.what();
}
@endcode
<h3> Use STL style iterators to move through nodes and attributes </h3>
TinyXML has two ways to iterate:

First Method:
@code
	for( child = parent->FirstChild( false ); child; child = child->NextSibling( false ) )
@endcode

Second Method:
@code
	child = 0;
	while( child = parent->IterateChildren( child ) )
@endcode

Although both methods work quite well, the syntax is not familiar.
TinyXML++ introduces iterators:
@code
ticpp::Iterator< ticpp::Node > child;
for ( child = child.begin( parent ); child != child.end(); child++ )
@endcode

Iterators have the added advantage of filtering by type:
@code
// Only iterates through Comment nodes
ticpp::Iterator< ticpp::Comment > child;
for ( child = child.begin( parent ); child != child.end(); child++ )
@endcode

@code
// Only iterates through Element nodes with value "ElementValue"
ticpp::Iterator< ticpp::Element > child( "ElementValue" );
for ( child = child.begin( parent ); child != child.end(); child++ )
@endcode

Finally, Iterators also work with Attributes
@code
ticpp::Iterator< ticpp::Attribute > attribute;
for ( attribute = attribute.begin( element ); attribute != attribute.end(); attribute++ )
@endcode

*/