Merge branch 'washwash-master'

Author: faif

3-tier.py

@@ -12,12 +12,11 @@ class Data(object):
  }
 
 def__get__(self, obj, klas):
-print("(Fetching from Data Store)")
+print("(Fetching from Data Store)")
 return{'products': self.products}
 
 
 classBusinessLogic(object):
-
 """ Business logic holding data store instances """
 
 data=Data()

README.md

@@ -25,6 +25,7 @@ Current Patterns:
 |[decorator](decorator.py)| wrap functionality with other functionality in order to affect outputs |
 |[facade](facade.py)| use one class as an API to a number of others |
 |[factory_method](factory_method.py)| delegate a specialized function/method to create instances |
+|[front_controller](front_controller.py)| single handler requests coming to the application |
 |[flyweight](flyweight.py)| transparently reuse existing instances of objects with similar/identical state |
 |[graph_search](graph_search.py)| (graphing algorithms, not design patterns) |
 |[lazy_evaluation](lazy_evaluation.py)| lazily-evaluated property pattern in Python |
@@ -36,6 +37,7 @@ Current Patterns:
 |[prototype](prototype.py)| use a factory and clones of a prototype for new instances (if instantiation is expensive) |
 |[proxy](proxy.py)| an object funnels operations to something else |
 |[publish_subscribe](publish_subscribe.py)| a source syndicates events/data to 0+ registered listeners |
+|[specification](specification.py)| business rules can be recombined by chaining the business rules together using boolean logic |
 |[state](state.py)| logic is org'd into a discrete number of potential states and the next state that can be transitioned to |
 |[strategy](strategy.py)| selectable operations over the same data |
 |[template](template.py)| an object imposes a structure but takes pluggable components |

adapter.py

@@ -37,7 +37,6 @@ def make_noise(self, octane_level):
 
 
 classAdapter(object):
-
 """
  Adapts an object by replacing methods.
  Usage:

front_controller.py

@@ -0,0 +1,75 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+
+"""
+@author: Gordeev Andrey <[email protected]>
+The controller provides a centralized entry point that controls and manages
+request handling.
+"""
+
+
+classMobileView(object):
+defshow_index_page(self):
+print('Displaying mobile index page')
+
+
+classTabletView(object):
+defshow_index_page(self):
+print('Displaying tablet index page')
+
+
+classDispatcher(object):
+def__init__(self):
+self.mobile_view=MobileView()
+self.tablet_view=TabletView()
+
+defdispatch(self, request):
+ifrequest.type==Request.mobile_type:
+self.mobile_view.show_index_page()
+elifrequest.type==Request.tablet_type:
+self.tablet_view.show_index_page()
+else:
+print('cant dispatch the request')
+
+
+classRequestController(object):
+""" front controller """
+def__init__(self):
+self.dispatcher=Dispatcher()
+
+defdispatch_request(self, request):
+ifisinstance(request, Request):
+self.dispatcher.dispatch(request)
+else:
+print('request must be a Request object')
+
+
+classRequest(object):
+""" request """
+
+mobile_type='mobile'
+tablet_type='tablet'
+
+def__init__(self, request):
+self.type=None
+request=request.lower()
+ifrequest==self.mobile_type:
+self.type=self.mobile_type
+elifrequest==self.tablet_type:
+self.type=self.tablet_type
+
+
+if__name__=='__main__':
+front_controller=RequestController()
+front_controller.dispatch_request(Request('mobile'))
+front_controller.dispatch_request(Request('tablet'))
+
+front_controller.dispatch_request(Request('desktop'))
+front_controller.dispatch_request('mobile')
+
+
+### OUTPUT ###
+# Displaying mobile index page
+# Displaying tablet index page
+# cant dispatch the request
+# request must be a Request object

specification.py

@@ -0,0 +1,117 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+
+"""
+@author: Gordeev Andrey <[email protected]>
+
+Specification provide recombination business logic by
+chaining together using boolean logic
+"""
+
+fromabcimportabstractmethod
+
+
+classSpecification(object):
+
+defand_specification(self, candidate):
+raiseNotImplementedError()
+
+defor_specification(self, candidate):
+raiseNotImplementedError()
+
+defnot_specification(self):
+raiseNotImplementedError()
+
+@abstractmethod
+defis_satisfied_by(self, candidate):
+pass
+
+
+classCompositeSpecification(Specification):
+@abstractmethod
+defis_satisfied_by(self, candidate):
+pass
+
+defand_specification(self, candidate):
+returnAndSpecification(self, candidate)
+
+defor_specification(self, candidate):
+returnOrSpecification(self, candidate)
+
+defnot_specification(self):
+returnNotSpecification(self)
+
+
+classAndSpecification(CompositeSpecification):
+_one=Specification()
+_other=Specification()
+
+def__init__(self, one, other):
+self._one=one
+self._other=other
+
+defis_satisfied_by(self, candidate):
+returnbool(self._one.is_satisfied_by(candidate) and
+self._other.is_satisfied_by(candidate))
+
+
+classOrSpecification(CompositeSpecification):
+_one=Specification()
+_other=Specification()
+
+def__init__(self, one, other):
+self._one=one
+self._other=other
+
+defis_satisfied_by(self, candidate):
+returnbool(self._one.is_satisfied_by(candidate) or
+self._other.is_satisfied_by(candidate))
+
+
+classNotSpecification(CompositeSpecification):
+_wrapped=Specification()
+
+def__init__(self, wrapped):
+self._wrapped=wrapped
+
+defis_satisfied_by(self, candidate):
+returnbool(notself._wrapped.is_satisfied_by(candidate))
+
+
+classUser(object):
+
+def__init__(self, super_user=False):
+self.super_user=super_user
+
+
+classUserSpecification(CompositeSpecification):
+
+defis_satisfied_by(self, candidate):
+returnisinstance(candidate, User)
+
+
+classSuperUserSpecification(CompositeSpecification):
+
+defis_satisfied_by(self, candidate):
+returngetattr(candidate, 'super_user', False)
+
+
+if__name__=='__main__':
+print('Specification')
+andrey=User()
+ivan=User(super_user=True)
+vasiliy='not User instance'
+
+root_specification=UserSpecification().\
+and_specification(SuperUserSpecification())
+
+print(root_specification.is_satisfied_by(andrey))
+print(root_specification.is_satisfied_by(ivan))
+print(root_specification.is_satisfied_by(vasiliy))
+
+
+### OUTPUT ###
+# Specification
+# False
+# True
+# False