From c4961fb1e600f27e37d9a8bf646e1c76afafd8b6 Mon Sep 17 00:00:00 2001
From: Scott Gasch <scott@gasch.org>
Date: Thu, 1 Sep 2022 11:42:34 -0700
Subject: Easier and more self documenting patterns for loading/saving
 Persistent state via pickle and json.

---
 cached/weather_forecast.py | 40 ++++++++++++++++++----------------------
 1 file changed, 18 insertions(+), 22 deletions(-)

(limited to 'cached/weather_forecast.py')

diff --git a/cached/weather_forecast.py b/cached/weather_forecast.py
index b8a20ed..7973bbb 100644
--- a/cached/weather_forecast.py
+++ b/cached/weather_forecast.py
@@ -56,7 +56,7 @@ class WeatherForecast:
 
 
 @persistent.persistent_autoloaded_singleton()  # type: ignore
-class CachedDetailedWeatherForecast(persistent.Persistent):
+class CachedDetailedWeatherForecast(persistent.PicklingFileBasedPersistent):
     def __init__(self, forecasts=None):
         if forecasts is not None:
             self.forecasts = forecasts
@@ -119,28 +119,24 @@ class CachedDetailedWeatherForecast(persistent.Persistent):
                     description=blurb,
                 )
 
-    @classmethod
+    @staticmethod
     @overrides
-    def load(cls) -> Any:
-        if persistent.was_file_written_within_n_seconds(
-            config.config['weather_forecast_cachefile'],
-            config.config['weather_forecast_stalest_acceptable'].total_seconds(),
-        ):
-            import pickle
-
-            with open(config.config['weather_forecast_cachefile'], 'rb') as rf:
-                weather_data = pickle.load(rf)
-                return cls(weather_data)
-        return None
+    def get_filename() -> str:
+        return config.config['weather_forecast_cachefile']
 
+    @staticmethod
     @overrides
-    def save(self) -> bool:
-        import pickle
-
-        with open(config.config['weather_forecast_cachefile'], 'wb') as wf:
-            pickle.dump(
-                self.forecasts,
-                wf,
-                pickle.HIGHEST_PROTOCOL,
-            )
+    def should_we_save_data(filename: str) -> bool:
         return True
+
+    @staticmethod
+    @overrides
+    def should_we_load_data(filename: str) -> bool:
+        return persistent.was_file_written_within_n_seconds(
+            filename,
+            config.config['weather_forecast_stalest_acceptable'].total_seconds(),
+        )
+
+    @overrides
+    def get_persistent_data(self) -> Any:
+        return self.forecasts
-- 
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