simulate named_scope by higher-order function + partial application in Python

gistfile1.txt

##
## named_scope example in Rails2
## (http://ryandaigle.com/articles/2008/3/24/what-s-new-in-edge-rails-has-finder-functionality)
##
class User < ActiveRecord::Base
  named_scope :active, :conditions => {:active => true}
  named_scope :recent, lambda { { :conditions => ['created_at > ?', 1.week.ago] } }
end

# same as User.find(:all, :conditions => {:active => true})
active_users = User.active

# same as User.find(:all, :conditions => ['created_at > ?', 1.week.ago])
recent_users = User.recent

# They're nest-able too!
recent_active_users = User.active.recent


##
## simulate named_scope with higher-order function + partial application
## in Python
##

def find_all(model_klass):
  def func(**kwargs):
    return model_klass.find('all', **kwargs)
  return func

def active(function):
  def func(**kwargs):
    if not kwargs.has_key('conditions'):
      kwargs['conditions'] = []
    kwargs['conditions'].append('active = true')
    ## or
    #kwargs.setdefault('conditions', []).append('active = true')
    return function(**kwargs)
  return func

import time

def recent(function):
  def func(**kwargs):
    now = time.time()
    sec = 60*60*24*7
    if not kwargs.has_key('conditions'):
      kwargs['conditions'] = []
    kwargs['conditions'].append('created_at > ' + (now - sec))
    ## or
    #kwargs.setdefault('conditions', []).append('created_at > ' + (now - sec))
    return function(**kwargs)
  return func


func                = find_all(User)
users               = find_all(User)()   # same as func()
active_users        = active(find_all(User))()
recent_active_users = recent(active(find_all(User)))()