Template filter to add paragraph-level permalinks to a block of HTML

paragraph_permalinks.py

from django import template
from BeautifulSoup import BeautifulSoup, Tag, NavigableString

register = template.Library()

@register.filter
def enumerate_paras(html):
    """
    Given a block of HTML, create id attributes on each
    paragraph (p) and write in a link at the end of each.
    
    >>> html = '''<p>First line.</p>
    ... <p>Second line.</p>'''
    >>> print enumerate_paras(html)
    <p id="p0">First line.<a href="#p0" title="Link to this paragraph"> #</a></p>
    <p id="p1">Second line.<a href="#p1" title="Link to this paragraph"> #</a></p>
    """
    
    soup = BeautifulSoup(html)
    paras = soup.findAll('p', recursive=False)
    for i, p in enumerate(paras):
        p['id'] = 'p%s' % i
        a = Tag(soup, 'a')
        a['href'] = '#p%s' % i
        a['title'] = 'Link to this paragraph'
        a.insert(0, NavigableString(' #')) # link text
        p.append(a) # just add our new a tag to the end of p's contents

    return soup.renderContents()