[XML-SIG] Experiences with xml-0.5

[Dieter Maurer]

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Based on our xml-0.5 release, I have made a small tool which adds
a hierarchical content table to HTML documents:

	URL:http://www.handshake.de/~dieter/pyprojects/addContentTable.html

I encountered three bugs:

 1. "xml.dom.core.Document"s methods "get_firstChild" and
    "get_lastChild" (inherited from "xml.dom.core.Node")
    fail to initialize the "ownerDocument" in the children
    correctly (patch attached).

 2. "xml.dom.write.OutputStream.write" folds successive '\n'
    into a single '\n' (i.e. it eliminates empty lines).
    This is bad for preformatted elements (patch attached).

 3. The "NodeList" returned by "get_childNodes" is live (as
    required by the standard).
    This can make children processing a bit hasardous (the downside
    of liveness), e.g.

	f= dom.createDocumentFragment()
	for c in node.childNodes: f.appendChild(c)
   
        will *NOT* put all children of "node" into "f" (it does for
	about every second, and leaves the remaining children)
	because the list is modified as a side effect.

	This is a well known problem with Pythons for loop.
	However, the standard workaround (using a slice copy
	of the list) does not work in this case, because
	"NodeList[:]" does not yield a NodeList but rather
	a "_nodeData".

Dieter

--------------FC5583E803777E8ABB8C4995
Content-Type: application/x-patch; name="docowner.pat"
Content-Description: Patch to provide "xml.dom.core.Document" its own
		     implementation of "get_firstChild" and "get_lastChild"
		     correctly initializing "ownerDocument" of the
		     children.

--- :core.py	Tue Dec 29 10:45:25 1998
+++ core.py	Tue Dec 29 14:59:35 1998
@@ -1041,6 +1041,27 @@
     def get_childNodes(self):
         return NodeList(self._node.children, self, self)
 
+    ## DM: the inherited method fails to set "._document" correctly
+    def get_firstChild(self):
+        """Return the first child of this node. If there is no such node, this
+        returns null."""
+
+        if self._node.children:
+            n = self._node.children[0]
+            return NODE_CLASS[ n.type ] (n, self, self)
+        else:
+            return None
+
+    ## DM: the inherited method fails to set "._document" correctly
+    def get_lastChild(self):
+        """Return the last child of this node. If there is no such node, this
+        returns null."""
+        if self._node.children:
+            n = self._node.children[-1]
+            return NODE_CLASS[ n.type ] (n, self, self)
+        else:
+            return None
+
     def get_documentElement(self):
         """Return the root element of the Document object, or None
         if there is no root element."""



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Content-Type: application/x-patch; name="emptyline.pat"
Content-Description: Patch to remove empty line removal in "xml.dom.writer"

--- :writer.py	Tue Dec 29 10:45:27 1998
+++ writer.py	Wed Dec 30 11:51:50 1998
@@ -16,7 +16,9 @@
 
 	def write(self, s):
 		#print 'write', `s`
-		self.file.write(re.sub('\n+', '\n', s))
+		#self.file.write(re.sub('\n+', '\n', s))
+	        # removing newlines is not a good idea for 'pre', e.g.
+		self.file.write(s)
 		if s and s[-1] == '\n':
 			self.new_line = 1
 		else:


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