poor man's rest resource in pyramid

gistfile1.py

class rest_resource(object):
    all_methods = frozenset([
        'head', 'get', 'post', 'put', 'patch', 'delete'])
        
    def __init__(self, **kw):
        self.kw = kw # view defaults
        
    def __call__(self, wrapped):
        # grab the supported methods from the class
        methods = self.all_methods.intersection(set(vars(wrapped).keys()))
        if 'get' in methods:
            methods.add('head')
            
        missing_methods = [m.upper() for m in self.all_methods - methods]
        allow = ['OPTIONS'] + list(missing_methods)
        
        def options(request):
            resp = request.response
            resp.allow = allow
            return resp
            
        def not_allowed(request):
            resp = request.response
            resp.allow = allow
            resp.status = 405
            return resp
        
        def callback(context, name, obj):
            config = context.config.with_package(info.module)
            
            # register all methods
            for method in methods:
                attr = method
                
                # redirect head requests to get
                # unless an explicit head method exists
                if method == 'head':
                    if not hasattr(wrapped, attr):
                        attr = 'get'
                        
                config.add_view(
                    wrapped,
                    attr=attr,
                    request_method=method.upper(),
                    **self.kw)
                
            # catch OPTIONS requests
            config.add_view(
                options,
                route_name=self.route_name,
                request_method='OPTIONS',
                **self.kw)
                
            # catch requests to unsupported methods to raise a 405
            # but allow other views to propagate to global notfound view
            config.add_view(
                not_allowed,
                route_name=self.route_name,
                context=HTTPNotFound,
                request_method=missing_methods,
                **self.kw)
            
        info = venusian.attach(wrapped, callback, category='pyramid')
        return wrapped

@rest_resource(route_name='root')
class Root(object):
    def __init__(self, request):
        self.request = request
        
    def get(self):
        return Response('GET request')
    
    def post(self):
        return Response('POST request')