Django model field inheritance

To inherit model field in Django is not enough simply inherit a field class. It is needed to add attribute __metaclass__ = models.SubfieldBase. After that, you can overload any method you want.

Use objects as a django view functions

To use objects instead of simple functions I apply the following method:

class Page(object):
    # Variables
    template = "main.html"
    vars = {}
    redirect_url = ""

    def __call__(self,request,*args,**kwargs):
        # Before calling a "main" content-generating method
        self.before_content(request,*args,**kwargs)
        # "Main" content-generating method. Must be declared in descendants
        self.content(request,*args,**kwargs)
        # After generating content
        self.after_content(request,*args,**kwargs)

        # if need to redirect - do it
        if self.redirect_url:
            # if is present special redirect-field in GET
            url = request.GET.get(REDIRECT_FIELD_NAME)
            return HttpResponseRedirect(url if url else self.redirect_url)
        # Just return early declared template
        return render_to_response(self.template, context_instance=RequestContext(request, self.vars))

    def before_content(self,request,*args,**kwargs):
        pass
    def after_content(self,request,*args,**kwargs):
        pass


class PageAuth(Page):
    def __call__(self,request,*args,**kwargs):
        if request.user.is_authenticated():
            return super(PageAuth,self).__call__(request,*args,**kwargs)
        return HttpResponseRedirect("{0}?{1}={2}".format(reverse(settings.LOGIN_VIEW),REDIRECT_FIELD_NAME,request.path))

class MainView(Page):
    def content(self,request,*args,**kwargs):
        self.template = 'template_name.html'
        self.vars['list'] = []

And has been changed url declarations. An example:

url(r'^$', MainView(), name="main_page")

(I couldn't find decision without using name parameter).