gistfile1.py

class SiteForm(twf.TableForm):
    action = 'save_site'
    
    children = [
        twf.HiddenField('id'),
        twf.TextField('name', validator=twv.UnicodeString(not_empty=True)),
        twf.TextField('url', validator=twv.URL(not_empty=True,  add_http=True, check_exists=True), 
            label_text="Website URL")
    ]

site_form = SiteForm('original_id')

class WebsiteMixin(object):
    """Additional methods for a Website object to contain"""
    @property
    def edit_form(self):
        """An edit form for a website"""
        return site_form(
            self.__dict__,
            id='site_form_%d' % self.id
        )