Skip to content

Instantly share code, notes, and snippets.

@vs9390
Last active April 27, 2019 06:51
Show Gist options
  • Save vs9390/bf540d32261523c0b0801ade0358d6aa to your computer and use it in GitHub Desktop.
Save vs9390/bf540d32261523c0b0801ade0358d6aa to your computer and use it in GitHub Desktop.
Facade design pattern Example
"""import on the first class #WeatherProvide """
import urllib
import urllib2
"""import on the second class #Parser"""
from datetime import datetime
import json
"""import on the third class #Cache"""
from datetime import timedelta
import pickle
#first class
class WeatherProvider(object):
def __init__(self):
self.api_url = 'http://api.openweathermap.org/data/2.5/forecast?APPID=1ed8ebdd15f882dfee35d22a296d3fd9&q={},{}'
def get_weather_data(self, city, country):
city = urllib.quote(city)
url = self.api_url.format(city, country)
return urllib2.urlopen(url).read()
#second class
class Parser(object):
def parse_weather_data(self, weather_data):
parsed = json.loads(weather_data)
start_date = None
result = []
for data in parsed['list']:
date = datetime.strptime(data['dt_txt'], '%Y-%m-%d %H:%M:%S')
start_date = start_date or date
if start_date.day != date.day:
return result
result.append(data['main']['temp'])
#third class
class Cache(object):
def __init__(self, filename):
self.filename = filename
def save(self, obj):
with open(self.filename, 'w') as file:
dct = {
'obj' : obj,
'expired': datetime.utcnow() + timedelta(hours=3)
}
pickle.dump(dct, file)
def load(self):
try:
with open (self.filename) as file:
result = pickle.load(file)
if result['expired'] > datetime.utcnow():
return result['obj']
except IOError:
pass
#fourth class (Kelvin to Celsius)
class Converter(object):
def from_kelvin_to_celcius(self, kelvin):
return kelvin - 273.15
#fifth class (receives iterable weather forecast for a day and calculates the median forecast)
class Weather(object):
"""docstring for Weather"""
def __init__(self, data):
result = 0
for r in data:
result += r
self.temperature = result / len(data)
# the FACADE class
class Facade(object):
def get_forecast(self, city, country):
cache = Cache('myfile')
cache_result = cache.load()
if cache_result:
return cache_result
else:
weather_provider = WeatherProvider()
weather_data = weather_provider.get_weather_data(city, country)
parser = Parser()
parsed_data = parser.parse_weather_data(weather_data)
weather = Weather(parsed_data)
converter = Converter()
temperature_celcius = converter.from_kelvin_to_celcius(weather.temperature)
cache.save(temperature_celcius)
return temperature_celcius
if __name__ == '__main__':
facade = Facade()
print facade.get_forecast('delhi', 'india')
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment