Sophie: lib64bakery2.6-devel-2.6.3-2mdv2010.0 x86

lib64bakery2.6-devel-2.6.3-2mdv2010.0.x86_64.rpm

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<h1 align="center">XML-Formatted Bakery Documents</h1>



<h2>Contents</h2>

<ul>

  <li><a href="#Introduction">Introduction</a></li>

  <li><a href="#Document">Create the Document class</a></li> 

</ul> 

 

<h2><a name="Introduction"></a>Introduction</h2> 

 

<blockquote> 
<p>The <a href="bakery_document_view.html">Document/View With Bakery</a> page explains how to derive a Document class for your application. But Bakery::Document doesn't help you to organise or parse the data in the file. And f you achieve that by using a custom data format then other applications will not be able to easily use the same document. To solve this problem, the Bakery::Document_XML class helps you to use an XML format to store your data. This has the following advantages:
<ul>
<li>You don't need to write complex document-parsing-and-building code - just use the XML parser's API. This means less code and more readable code.</li>
<li>Instead of checking the document's structure with complicated code, you can validate it with a DTD.</li>
<li>Other applications can work with your document.</li>
<li>The file is human-readable, so you can investigate problems in the file.</li>
</ul>
</p>

</blockquote> 

 
<h2><a name="Document"></a>Create the Document class</h2>                 

              
<blockquote>

  <p>Derive a Document class from Bakery::Document_XML. You don't need to override load_after() and save_after(), because Document_XML can do that for XML documents in general.</p>             
  <p>e.g.</p>             

            
  <blockquote>
    <pre>
class DocExample : public Bakery::Document_XML
{
public:
  DocExample();
  virtual ~DocExample();

  void set_something(const std::string&amp; strSomething);
  std::string get_something();

protected:
  xmlpp::Node* get_node_something(); //Gets <something>
};
</pre>
  </blockquote>

<p>As in the other examples, you should specify the file extension in the constructor. But you should also specify the name of the XML file's DTD, and the name of the top-level XML node. These will be used to create new empty Documents.</p>
 <blockquote>
    <pre>
DocExample::DocExample()
{
  set_file_extension("bakery_example_xml");
 
  set_DTD_Name("example_xml_doc.dtd");
  set_DTD_RootNodeName("example_xml_doc");
}
</pre>
</blockquote>

  <p>As in the other examples, when you implement methods like set_something(), which changes data in your 
  document, you should call Document::set_modified(true).</p>
  <p>In this example there is also a get_node_something() convenience method, just to reduce code duplication. Notice that we use the libxml++ Node class from the xmlpp namespace.</p>
 <blockquote>
    <pre>
void DocExample::set_something(const std::string& strSomething)
{
  try
  {
    set_node_attribute_value(get_node_something(), "someval", strSomething);
    set_modified();
  }
  catch(const std::exception& ex)
  {
    //HandleError(ex); 
  }
}

std::string DocExample::get_something()
{
  std::string strValue;

  try
  {
    strValue = get_node_attribute_value(get_node_something(), "someval");
  }
  catch(const std::exception& ex)
  {
    //HandleError(ex); 
  }

  return strValue;
}

xmlpp::Node* DocExample::get_node_something()
{
  try
  { 
    xmlpp::Node* nodeRoot = get_node_document();
    return get_node_child_named_with_add(nodeRoot, "something");
  }
  catch(const std::exception& ex)
  {
    //HandleError(ex);
    return 0;
  }
}
</pre>
</blockquote>

<p>You just need to use the libxml++ xmlpp::DomParser API, along with some convenience methods in Bakery::Document_XML, to navigate, read, and build your document. Bakery::Document_XML will take care of actually reading the XML into memory and writing it back to disk at the appropriate time.</p>
  
</blockquote>
</h2>
                 

<p align="center"><font size="1">Copyright © 2001, Murray Cumming. Verbatim        

copying and distribution of this entire article is permitted in any medium,        

provided this notice is preserved.</font></p>       

                

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