@register.inclusion_tag("form_tools/render_field.html")
def render_field(field,attributes=''):
    """ render a field with its errors, optionally passing in 
        attributes eg.:  
        {% render_field form.name "cols=40,rows=5,class=text,tabindex=2" %}

        this is equivalent to
        <p>{{form.name.errors}}</p>
        {{ form.name }}

        but will also add the custom attributes
    """
    return {'errors':field.errors,'widget':make_widget(field,attributes)}

def make_widget(field,attributes):
    attr = {}
    if attributes:
        attrs = attributes.split(",")
        if attrs:
            for at in attrs:
                key,value = at.split("=")
                attr[key] = value
    return field.as_widget(attrs=attr)

## render_field.html
{% if errors %}<p>{{ errors }}</p>{% endif %}
{{ widget }}