Mailman 3 xml generator that uses the with statement - Python-ideas

12 Sep 2008

Here is a quick and dirty draft of a xml generator that uses the with statement:
http://twoday.tuwien.ac.at/pub/files/XmlMarkup (ZIP, 3 KB)
It is inspired by rubies XmlMarkup class.
Brief usage:
...
from __future__ import with_statement
from XmlMarkup  import *
import sys
with XmlMarkup(sys.stdout) as xm:
    with xm.root:
        xm.text('foo')
        with xm.prefixMapping('x','http://example.com/x'):
            with xm.tag.ns('http://example.com/x'):
                xm.comment('comment')
            with xm['text']:
                xm.text('bar')
        with xm.tag(foo='bar',egg='spam'):
            pass
<?xml version="1.0" encoding="utf-8"?>
<root>foo<x:tag
xmlns:x="http://example.com/x"><!--comment--></x:tag><text>bar</text><tag
foo="bar" egg="spam"></tag></root>
I'm not 100% sure
about some parts of the 'syntax', though.
E.g. maybe change this:
...
with xm.tag(x='y').ns('...'):
    with xm.tag:
        ...
into this:
...
with xm.tag('...',x='y'):
    with xm.tag():
        ...
This Syntax is more concise than those unhandy and error prone
beginElement/endElement calls (endElement needs the name as argument, too!).
This way you never forget to close a tag again. :)
It even provides a simple way to embed arbitrary data:
...
with xm.text as text:
# text is a pseudo file object
with XmlMarkup(text) as xm2:
    # things you generate with xm2 will be escaped

And I added a way to generate DTDs:
...
with xm.dtd('foo') as dtd:
    dtd.element('a',oneof('x','y',PCDATA))
    dtd.element('x',('egg','bacon',many('spam')))
    dtd.attlist('a',att1 = (CDATA, DEFAULT, 'value'), att2 = (ID, REQUIRED))
    dtd.entity('ent','value')
What do you think? :)
-panzi