refactor: apply singleton pattern in app/services

Author: FrankX-xzh

app/location/__init__.py

@@ -4,19 +4,6 @@
 from ..utils.populations import country_population
 
 
-
-class Locations:
-    def __init__(self,locations: list[Location]):
-        self.locations = locations
-
-    def add_service(self,location):
-        self.locations.append(location)
-
-    def get_location(self):
-        return locations
-
-
-
 # pylint: disable=redefined-builtin,invalid-name
 class Location:  # pylint: disable=too-many-instance-attributes
     """

app/services/location/__init__.py

@@ -1,17 +1,17 @@
 """app.services.location"""
 from abc import ABC, abstractmethod
 
+def singleton(cls):
+    instances = {}
 
-class LocationServices:
-    def __init__(self,location_services: list[LocationService]):
-        self.location_services = location_services
+    def wrapper(*args, **kwargs):
+        if cls not in instances:
+            instances[cls] = cls(*args, **kwargs)
+        return instances[cls]
 
-    def add_service(self,location_service):
-        self.location_services.append(location_service)
-
-    def get_service(self):
-        return location_services
+    return wrapper
 
+@singleton
 class LocationService(ABC):
     """
     Service for retrieving locations.

app/services/location/csbs.py

@@ -14,7 +14,7 @@
 
 LOGGER = logging.getLogger("services.location.csbs")
 
-
+@singleton
 class CSBSLocationService(LocationService):
     """
     Service for retrieving locations from csbs

app/services/location/jhu.py

@@ -21,6 +21,7 @@
 PID = os.getpid()
 
 
+@singleton
 class JhuLocationService(LocationService):
     """
     Service for retrieving locations from Johns Hopkins CSSE (https://github.com/CSSEGISandData/COVID-19).

app/services/location/nyt.py

@@ -16,6 +16,7 @@
 LOGGER = logging.getLogger("services.location.nyt")
 
 
+@singleton
 class NYTLocationService(LocationService):
     """
     Service for retrieving locations from New York Times (https://github.com/nytimes/covid-19-data).