Django: How do I use a different form_class with django-registration

I want django-registration (version 0.8) to 开发者_运维问答use my custom form rather than the default one. However, I want to continue to use the default django-registration view. What should the rest of the line below look like to achieve this?

(r'^accounts/register'...),

I've tried this below but get a syntax error:

(r'^accounts/register/$', 
         'registration.views.register', 
         {'form_class': 'MyRegistrationForm'}, name='registration_register'),

And when I try this one below I get register() takes at least 2 non-keyword arguments (1 given)

(r'^accounts/register/$',      
    'registration.views.register',             
    {'form_class':'MyRegistrationForm'}),

Looking at the views.register function,

def register(request, backend, success_url=None, form_class=None,
             disallowed_url='registration_disallowed',
             template_name='registration/registration_form.html',
             extra_context=None):

you can see that backend is a required argument. Try the following:

url(r'^accounts/register/$', 
         'registration.views.register', 
         {'form_class': MyRegistrationForm,
          'backend':'registration.backends.default.DefaultBackend'},
         name='registration_register'),

note that you need to use url(r'^...) if you wish to name your url.