Substantial re-organization of the DOM documentation. The abstract API

is now separated from the supplied standard implementation.  Not all
interfaces are documented yet, but the structure is better set up to do
so.

There is still a lot to do here, but the shape of the documentation is
coming into line.

1 files changed, 294 insertions, 0 deletions

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+\section{\module{xml.dom.minidom} ---
+         Lightweight DOM implementation}
+
+\declaremodule{standard}{xml.dom.minidom}
+\modulesynopsis{Lightweight Document Object Model (DOM) implementation.}
+\moduleauthor{Paul Prescod}{paul@prescod.net}
+\sectionauthor{Paul Prescod}{paul@prescod.net}
+\sectionauthor{Martin v. L\"owis}{loewis@informatik.hu-berlin.de}
+
+\versionadded{2.0}
+
+\module{xml.dom.minidom} is a light-weight implementation of the
+Document Object Model interface.  It is intended to be
+simpler than the full DOM and also significantly smaller.
+
+DOM applications typically start by parsing some XML into a DOM.  With
+\module{xml.dom.minidom}, this is done through the parse functions:
+
+\begin{verbatim}
+from xml.dom.minidom import parse, parseString
+
+dom1 = parse('c:\\temp\\mydata.xml') # parse an XML file by name
+
+datasource = open('c:\\temp\\mydata.xml')
+dom2 = parse(datasource)   # parse an open file
+
+dom3 = parseString('<myxml>Some data<empty/> some more data</myxml>')
+\end{verbatim}
+
+The parse function can take either a filename or an open file object. 
+
+\begin{funcdesc}{parse}{filename_or_file{, parser}}
+  Return a \class{Document} from the given input. \var{filename_or_file}
+  may be either a file name, or a file-like object. \var{parser}, if
+  given, must be a SAX2 parser object. This function will change the
+  document handler of the parser and activate namespace support; other
+  parser configuration (like setting an entity resolver) must have been
+  done in advance.
+\end{funcdesc}
+
+If you have XML in a string, you can use the
+\function{parseString()} function instead:
+
+\begin{funcdesc}{parseString}{string\optional{, parser}}
+  Return a \class{Document} that represents the \var{string}. This
+  method creates a \class{StringIO} object for the string and passes
+  that on to \function{parse}.
+\end{funcdesc}
+
+Both functions return a \class{Document} object representing the
+content of the document.
+
+You can also create a \class{Document} node merely by instantiating a 
+document object.  Then you could add child nodes to it to populate
+the DOM:
+
+\begin{verbatim}
+from xml.dom.minidom import Document
+
+newdoc = Document()
+newel = newdoc.createElement("some_tag")
+newdoc.appendChild(newel)
+\end{verbatim}
+
+Once you have a DOM document object, you can access the parts of your
+XML document through its properties and methods.  These properties are
+defined in the DOM specification.  The main property of the document
+object is the \member{documentElement} property.  It gives you the
+main element in the XML document: the one that holds all others.  Here
+is an example program:
+
+\begin{verbatim}
+dom3 = parseString("<myxml>Some data</myxml>")
+assert dom3.documentElement.tagName == "myxml"
+\end{verbatim}
+
+When you are finished with a DOM, you should clean it up.  This is
+necessary because some versions of Python do not support garbage
+collection of objects that refer to each other in a cycle.  Until this
+restriction is removed from all versions of Python, it is safest to
+write your code as if cycles would not be cleaned up.
+
+The way to clean up a DOM is to call its \method{unlink()} method:
+
+\begin{verbatim}
+dom1.unlink()
+dom2.unlink()
+dom3.unlink()
+\end{verbatim}
+
+\method{unlink()} is a \module{xml.dom.minidom}-specific extension to
+the DOM API.  After calling \method{unlink()} on a node, the node and
+its descendents are essentially useless.
+
+\begin{seealso}
+  \seetitle[http://www.w3.org/TR/REC-DOM-Level-1/]{Document Object
+            Model (DOM) Level 1 Specification}
+           {The W3C recommendation for the
+            DOM supported by \module{xml.dom.minidom}.}
+\end{seealso}
+
+
+\subsection{DOM objects \label{dom-objects}}
+
+The definition of the DOM API for Python is given as part of the
+\refmodule{xml.dom} module documentation.  This section lists the
+differences between the API and \refmodule{xml.dom.minidom}.
+
+
+\begin{methoddesc}{unlink}{}
+Break internal references within the DOM so that it will be garbage
+collected on versions of Python without cyclic GC.  Even when cyclic
+GC is available, using this can make large amounts of memory available
+sooner, so calling this on DOM objects as soon as they are no longer
+needed is good practice.  This only needs to be called on the
+\class{Document} object, but may be called on child nodes to discard
+children of that node.
+\end{methoddesc}
+
+\begin{methoddesc}{writexml}{writer}
+Write XML to the writer object.  The writer should have a
+\method{write()} method which matches that of the file object
+interface.
+\end{methoddesc}
+
+\begin{methoddesc}{toxml}{}
+Return the XML that the DOM represents as a string.
+\end{methoddesc}
+
+The following standard DOM methods have special considerations with
+\refmodule{xml.dom.minidom}:
+
+\begin{methoddesc}{cloneNode}{deep}
+Although this method was present in the version of
+\refmodule{xml.dom.minidom} packaged with Python 2.0, it was seriously
+broken.  This has been corrected for subsequent releases.
+\end{methoddesc}
+
+
+\subsection{DOM Example \label{dom-example}}
+
+This example program is a fairly realistic example of a simple
+program. In this particular case, we do not take much advantage
+of the flexibility of the DOM.
+
+\begin{verbatim}
+import xml.dom.minidom
+
+document = """\
+<slideshow>
+<title>Demo slideshow</title>
+<slide><title>Slide title</title>
+<point>This is a demo</point>
+<point>Of a program for processing slides</point>
+</slide>
+
+<slide><title>Another demo slide</title>
+<point>It is important</point>
+<point>To have more than</point>
+<point>one slide</point>
+</slide>
+</slideshow>
+"""
+
+dom = xml.dom.minidom.parseString(document)
+
+space = " "
+def getText(nodelist):
+    rc = ""
+    for node in nodelist:
+        if node.nodeType == node.TEXT_NODE:
+            rc = rc + node.data
+    return rc
+
+def handleSlideshow(slideshow):
+    print "<html>"
+    handleSlideshowTitle(slideshow.getElementsByTagName("title")[0])
+    slides = slideshow.getElementsByTagName("slide")
+    handleToc(slides)
+    handleSlides(slides)
+    print "</html>"
+
+def handleSlides(slides):
+    for slide in slides:
+       handleSlide(slide)
+
+def handleSlide(slide):
+    handleSlideTitle(slide.getElementsByTagName("title")[0])
+    handlePoints(slide.getElementsByTagName("point"))
+
+def handleSlideshowTitle(title):
+    print "<title>%s</title>" % getText(title.childNodes)
+
+def handleSlideTitle(title):
+    print "<h2>%s</h2>" % getText(title.childNodes)
+
+def handlePoints(points):
+    print "<ul>"
+    for point in points:
+        handlePoint(point)
+    print "</ul>"
+
+def handlePoint(point):
+    print "<li>%s</li>" % getText(point.childNodes)
+
+def handleToc(slides):
+    for slide in slides:
+        title = slide.getElementsByTagName("title")[0]
+        print "<p>%s</p>" % getText(title.childNodes)
+
+handleSlideshow(dom)
+\end{verbatim}
+
+
+\subsection{minidom and the DOM standard \label{minidom-and-dom}}
+
+\refmodule{xml.dom.minidom} is basically a DOM 1.0-compatible DOM with
+some DOM 2 features (primarily namespace features). 
+
+Usage of the DOM interface in Python is straight-forward.  The
+following mapping rules apply:
+
+\begin{itemize}
+\item Interfaces are accessed through instance objects. Applications
+      should not instantiate the classes themselves; they should use
+      the creator functions available on the \class{Document} object.
+      Derived interfaces support all operations (and attributes) from
+      the base interfaces, plus any new operations.
+
+\item Operations are used as methods. Since the DOM uses only
+      \keyword{in} parameters, the arguments are passed in normal
+      order (from left to right).   There are no optional
+      arguments. \keyword{void} operations return \code{None}.
+
+\item IDL attributes map to instance attributes. For compatibility
+      with the OMG IDL language mapping for Python, an attribute
+      \code{foo} can also be accessed through accessor methods
+      \method{_get_foo()} and \method{_set_foo()}.  \keyword{readonly}
+      attributes must not be changed; this is not enforced at
+      runtime.
+
+\item The types \code{short int}, \code{unsigned int}, \code{unsigned
+      long long}, and \code{boolean} all map to Python integer
+      objects.
+
+\item The type \code{DOMString} maps to Python strings.
+      \refmodule{xml.dom.minidom} supports either byte or Unicode
+      strings, but will normally produce Unicode strings.  Attributes
+      of type \code{DOMString} may also be \code{None}.
+
+\item \keyword{const} declarations map to variables in their
+      respective scope
+      (e.g. \code{xml.dom.minidom.Node.PROCESSING_INSTRUCTION_NODE});
+      they must not be changed.
+
+\item \code{DOMException} is currently not supported in
+      \refmodule{xml.dom.minidom}.  Instead,
+      \refmodule{xml.dom.minidom} uses standard Python exceptions such
+      as \exception{TypeError} and \exception{AttributeError}.
+
+\item \class{NodeList} objects are implemented as Python's built-in
+      list type, so don't support the official API, but are much more
+      ``Pythonic.''
+
+\item \class{NamedNodeMap} is implemented by the class
+      \class{AttributeList}.  This should not impact user code.
+\end{itemize}
+
+
+The following interfaces have no implementation in
+\refmodule{xml.dom.minidom}:
+
+\begin{itemize}
+\item DOMTimeStamp
+
+\item DocumentType (added for Python 2.1)
+
+\item DOMImplementation (added for Python 2.1)
+
+\item CharacterData
+
+\item CDATASection
+
+\item Notation
+
+\item Entity
+
+\item EntityReference
+
+\item DocumentFragment
+\end{itemize}
+
+Most of these reflect information in the XML document that is not of
+general utility to most DOM users.