I have a class
The point of this class is to provide an uncluttered interface
to Document Creation
from xml.dom.minidom import getDOMImplementation
class NpDOMDocumentFactory:
A DOM Document Factory convenience class
# make these private by convention
__DOMImplementation = getDOMImplementation()
__defaultNamespaceUri = http://nuldomain.com/;
__defaultQualifiedName = root
__defaultDoctype = __DOMImplementation.createDocumentType(HTML,
-//W3C//DTD HTML
4.01//EN,
Trying to make things private is a throwback to Java. In Python
the tendency is to just leave everything public. And private is with
one underbar/underscore.
http://www.w3.org/TR/html4/strict.dtd;)
#params required for the createDocument method on DOMImplementation
#DOMImplementation.createDocument(namespaceUri, qualifiedName, doctype)
#get a default document with the root element initialised to root
def getDOMDocument(self):
print(no args)
return self.__DOMImplementation.createDocument(None, root, None)
#allow a user to specify the namespaceUri node name
def getDOMDocument(self, namespaceUri=__defaultNamespaceUri):
return self.__DOMImplementation.createDocument(namespaceUri, root,
None)
#allow a user to specify the namespaceUri and a qualifiedName
def getDOMDocument(self, namespaceUri=__defaultNamespaceUri,
qualifiedName=__defaultQualifiedName):
return self.__DOMImplementation.createDocument(namespaceUri,
qualifiedName, None)
#allow a user to specify the namespaceUri, a qualifiedName and a doctype
def getDOMDocument(self, namespaceUri=__defaultNamespaceUri,
qualifiedName=__defaultQualifiedName, docType=__defaultDoctype):
print(3 args)
return self.__DOMImplementation.createDocument(namespaceUri,
qualifiedName, docType)
#end NpDOMDocumentFactory
factory = NpDOMDocumentFactory()
print(factory.getDOMDocument().toxml())
when I pass this to python I get the following
lipska@ubuntu:~/python/dev/classes/com/nuldomain/xml$ python3.2
NpDOMDocumentFactory.py
3 args
?xml version=1.0 ?!DOCTYPE HTML PUBLIC '-//W3C//DTD HTML 4.01//EN'
'http://www.w3.org/TR/html4/strict.dtd'root/
I have absolutely no idea why a method that requires three arguments is being
called when I intend the no args method to be called
Python does not have polymorphism in the same manner as Java.
Instead of creating different methods with a different number of
arguments, you create one method with optional arguments, i.e.
keyword arguments.
def function( something=None ):
print(something)
This creates a function where the argument 'something' is optional.
If nothing is passed in, then something will default to None. If
something is passed in as either a positional or keyword argument--
func('test') or func(something='test')--then the value of something
will be whatever is passed in.
Now applying that to your method I see you have three different
return statements.
return self.__DOMImplementation.createDocument(namespaceUri,
qualifiedName, docType)
return self.__DOMImplementation.createDocument(namespaceUri,
qualifiedName, None)
return self.__DOMImplementation.createDocument(namespaceUri,
root, None)
So I will use the method definition.
def getDOMDocument(self, namespaceUri=__defaultNamespaceUri,
qualifiedName=__defaultQualifiedName, docType=__defaultDoctype):
return self.__DOMImplementation.createDocument(namespaceUri,
qualifiedName, docType)
Now in order to get the same returns as above I will call
it with the following options.
self.getDOMDocument(namespace_url, qualified_name, doc_type )
self.getDOMDocument(namespace_url, qualified_name, docType=None )
self.getDOMDocument(namespace_url, docType=None, qualifiedName=root )
The last line can also be written entirely as positional arguments.
self.getDOMDocument(namespace_url, root, None )
Or if you want to use all the default arguments
self.getDOMDocument()
Ramit
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