Python-Design-Patterns mvc
mvc Model
Python-Design-Patterns mvc
# file: 'mvc.py'
#!/usr/bin/env python
# -*- coding: utf-8 -*-
"""
*TL;DR80
Separates data in GUIs from the ways it is presented, and accepted.
"""
class Model(object):
def __iter__(self):
raise NotImplementedError
def get(self, item):
"""Returns an object with a .items() call method
that iterates over key,value pairs of its information."""
raise NotImplementedError
@property
def item_type(self):
raise NotImplementedError
class ProductModel(Model):
class Price(float):
"""A polymorphic way to pass a float with a particular
__str__ functionality."""
def __str__(self):
return "{:.2f}".format(self)
products = {
'milk': {'price': Price(1.50), 'quantity': 10},
'eggs': {'price': Price(0.20), 'quantity': 100},
'cheese': {'price': Price(2.00), 'quantity': 10},
}
item_type = 'product'
def __iter__(self):
for item in self.products:
yield item
def get(self, product):
try:
return self.products[product]
except KeyError as e:
raise KeyError((str(e) + " not in the model's item list."))
class View(object):
def show_item_list(self, item_type, item_list):
raise NotImplementedError
def show_item_information(self, item_type, item_name, item_info):
"""Will look for item information by iterating over key,value pairs
yielded by item_info.items()"""
raise NotImplementedError
def item_not_found(self, item_type, item_name):
raise NotImplementedError
class ConsoleView(View):
def show_item_list(self, item_type, item_list):
print(item_type.upper() + ' LIST:')
for item in item_list:
print(item)
print('')
@staticmethod
def capitalizer(string):
return string[0].upper() + string[1:].lower()
def show_item_information(self, item_type, item_name, item_info):
print(item_type.upper() + ' INFORMATION:')
printout = 'Name: %s' % item_name
for key, value in item_info.items():
printout += ', ' + self.capitalizer(str(key)) + ': ' + str(value)
printout += '\n'
print(printout)
def item_not_found(self, item_type, item_name):
print('That %s "%s" does not exist in the records' % (item_type, item_name))
class Controller(object):
def __init__(self, model, view):
self.model = model
self.view = view
def show_items(self):
items = list(self.model)
item_type = self.model.item_type
self.view.show_item_list(item_type, items)
def show_item_information(self, item_name):
try:
item_info = self.model.get(item_name)
except Exception:
item_type = self.model.item_type
self.view.item_not_found(item_type, item_name)
else:
item_type = self.model.item_type
self.view.show_item_information(item_type, item_name, item_info)
if __name__ == '__main__':
model = ProductModel()
view = ConsoleView()
controller = Controller(model, view)
controller.show_items()
controller.show_item_information('cheese')
controller.show_item_information('eggs')
controller.show_item_information('milk')
controller.show_item_information('arepas')
### OUTPUT ###
# PRODUCT LIST:
# cheese
# eggs
# milk
#
# PRODUCT INFORMATION:
# Name: Cheese, Price: 2.00, Quantity: 10
#
# PRODUCT INFORMATION:
# Name: Eggs, Price: 0.20, Quantity: 100
#
# PRODUCT INFORMATION:
# Name: Milk, Price: 1.50, Quantity: 10
#
# That product "arepas" does not exist in the records
mvc.py
