vs interface |
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class UserCollection:
#
def linear_search_for(user: User) -> bool:
for saved_user in self._all_users:
if saved_user == user:
return True
return False , , UserCollection. , . , "" , "" :
class UserCollection:
#
def includes(user: User) -> bool:
''' ''', . , , , , :
from utils import DatabaseConfig
# DatabaseConfig ,
#
def is_password_valid(password: str) -> bool:
min_length = DatabaseConfig().password_min_length
return len(password) > min_length , , . , , , . , . min_length:
# DatabaseConfig
def is_password_valid(password: str, min_length: int) -> bool:
return len(password) > min_length DatabaseConfig . , .
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# utils.py
class DatabaseConfig:
''' '''
config = DatabaseConfig()
#
def is_password_valid(password: str, min_length: int) -> bool:
return len(password) > min_length# user.py
from utils import is_password_valid
#
# DatabaseConfig
class User:
def __init__(self, name: str, password: str):
self.name = name
self.password = password
def change_password(self, new_password: str) -> None:
if not is_password_valid(new_password, min_length=6):
raise Exception('Invalid password')
self.password = new_password User , , , . , from utils import is_password_valid, , . . DatabaseConfig .
, , . . "Smalltalk Best Practice Patterns" :
There are a few things I look for that are good predictors of whether a project is in good shape.
Replacing objects Good style leads to easily replaceable objects. In a really good system, every time the user says I want to do this radically different thing, the developer says, Oh, Ill have to make a new kind of X and plug it in.
, , . Python abc, , NotImplementedError.
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# weather.py
from typing import List, NamedTuple
class Weather(NamedTuple):
max_temperature_: int
avg_temperature_: int
min_temperature_c: int
class WeatherService:
def get_today_weather(self, city: str) -> Weather:
raise NotImplementedError
def get_week_weather(self, city: str) -> List[Weather]:
raise NotImplementedError, , , , :
# test.py
from client import WeatherWidget
from weather import Weather, WeatherService
class FakeWeatherService(WeatherService):
def __init__(self):
self._weather = Weather(max_temperature_ = 24,
avg_temperature_ = 20,
min_temperature_c = 16)
def get_today_weather(self, city: str) -> Weather:
return self._weather
def get_week_weather(self, city: str) -> List[Weather]:
raise [self._weather for _ in range(7)]
def test_present_today_weather_in_string_format():
weather_service = FakeWeatherService()
widget = WeatherWidget(weather_service)
expected_string = ('Maximum Temperature: 24 C'
'Average Temperature: 20 C'
'Minimum Temperature: 16 C')
assert widget.today_weather == expected_string : , , , WeatherService.
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