[XML-SIG] RE: converting integer to string

[Andrew M. Kuchling]

Tim Peters quoted:
>> Is there a function in Python to convert an integer value to
>> a string?

Here's an XML-based variant; the integer is marshalled into a simple
format, and the resulting XML file is then parsed into a Document
Object Model Tree.  Obtaining the string value is then simply a matter
of retrieving the single 'integer' element in the tree, and getting
the value of its first child, which must be a Text node.  

A useful property of this implementation is that it will return the
string value of the first integer in a tuple or list.  Actually,
given a recursive data structure, it should return the string value of
the first integer found in a preorder traversal of the list.

So, for example:

print `xml_int2str( 5 )`
print `xml_int2str( (6,5) )`
print `xml_int2str( ("stupid string", 7,5) )`

outputs

'5'
'6'
'7'

def xml_int2str(n):
    # Marshal the integer, sticking the result in a StringIO object.
    import StringIO
    mem_file = StringIO.StringIO()
    from xml import marshal
    data = marshal.dump( n, mem_file )
    mem_file.seek(0)

    # mem_file now contains something like:
    # <?xml version="1.0"?>
    # <!DOCTYPE marshal SYSTEM "marshal.dtd">
    # <marshal><integer>5</integer></marshal>
    # Parse this and convert it to a DOM tree.
    from xml.sax import saxexts
    from xml.dom.sax_builder import SaxBuilder
    p = saxexts.make_parser()
    dh = SaxBuilder()
    p.setDocumentHandler(dh)
    p.parseFile( mem_file )

    # Get the root Document node.
    doc = dh.document

    # List all the 'integer' elements in the tree, and retrieve the
    # value of the child of the first one, which should be a Text node
    # containing the string '5'. 
    integer_list = doc.getElementsByTagName( 'integer' )
    integer_elem = integer_list[0]
    children = integer_elem.get_childNodes()
    return children[0].get_nodeValue()

-- 
A.M. Kuchling			http://starship.skyport.net/crew/amk/
REMIND ME AGAIN, he said, HOW THE LITTLE HORSE-SHAPED ONES MOVE.
    -- Death on symbolic last games, in Terry Pratchett's _Small Gods_