More cleanup, yey!

[python_utils.git] / persistent.py

diff --git a/persistent.py b/persistent.py
index 8829d6de657c213845356b7c32caa2a644a1eb54..c902313eb4a28cb4635779f584f8775a2b646d35 100644 (file)
--- a/persistent.py
+++ b/persistent.py
@@ -1,11 +1,15 @@
 #!/usr/bin/env python3
 
-from abc import ABC, abstractmethod
+"""A Persistent is just a class with a load and save method.  This
+module defines the Persistent base and a decorator that can be used to
+create a persistent singleton that autoloads and autosaves."""
+
 import atexit
 import datetime
 import enum
 import functools
 import logging
+from abc import ABC, abstractmethod
 from typing import Any
 
 import file_utils
@@ -20,6 +24,7 @@ class Persistent(ABC):
     and implement their save() and load() methods.
 
     """
+
     @abstractmethod
     def save(self) -> bool:
         """
@@ -63,17 +68,14 @@ def was_file_written_today(filename: str) -> bool:
         return False
 
     mtime = file_utils.get_file_mtime_as_datetime(filename)
+    assert mtime is not None
     now = datetime.datetime.now()
-    return (
-        mtime.month == now.month and
-        mtime.day == now.day and
-        mtime.year == now.year
-    )
+    return mtime.month == now.month and mtime.day == now.day and mtime.year == now.year
 
 
 def was_file_written_within_n_seconds(
-        filename: str,
-        limit_seconds: int,
+    filename: str,
+    limit_seconds: int,
 ) -> bool:
     """Returns True if filename was written within the pas limit_seconds
     seconds.
@@ -83,6 +85,7 @@ def was_file_written_within_n_seconds(
         return False
 
     mtime = file_utils.get_file_mtime_as_datetime(filename)
+    assert mtime is not None
     now = datetime.datetime.now()
     return (now - mtime).total_seconds() <= limit_seconds
 
@@ -93,9 +96,10 @@ class PersistAtShutdown(enum.Enum):
     to disk.  See details below.
 
     """
-    NEVER = 0,
-    IF_NOT_LOADED = 1,
-    ALWAYS = 2,
+
+    NEVER = (0,)
+    IF_NOT_LOADED = (1,)
+    ALWAYS = (2,)
 
 
 class persistent_autoloaded_singleton(object):
@@ -118,15 +122,17 @@ class persistent_autoloaded_singleton(object):
     implementation.
 
     """
+
     def __init__(
-            self,
-            *,
-            persist_at_shutdown: PersistAtShutdown = PersistAtShutdown.IF_NOT_LOADED):
+        self,
+        *,
+        persist_at_shutdown: PersistAtShutdown = PersistAtShutdown.IF_NOT_LOADED,
+    ):
         self.persist_at_shutdown = persist_at_shutdown
         self.instance = None
 
     def __call__(self, cls: Persistent):
-        @functools.wraps(cls)
+        @functools.wraps(cls)  # type: ignore
         def _load(*args, **kwargs):
 
             # If class has already been loaded, act like a singleton
@@ -134,33 +140,30 @@ class persistent_autoloaded_singleton(object):
             # memory.
             if self.instance is not None:
                 logger.debug(
-                    f'Returning already instantiated singleton instance of {cls.__name__}.'
+                    'Returning already instantiated singleton instance of %s.', cls.__name__
                 )
                 return self.instance
 
             # Otherwise, try to load it from persisted state.
             was_loaded = False
-            logger.debug(f'Attempting to load {cls.__name__} from persisted state.')
+            logger.debug('Attempting to load %s from persisted state.', cls.__name__)
             self.instance = cls.load()
             if not self.instance:
                 msg = 'Loading from cache failed.'
                 logger.warning(msg)
-                logger.debug(f'Attempting to instantiate {cls.__name__} directly.')
+                logger.debug('Attempting to instantiate %s directly.', cls.__name__)
                 self.instance = cls(*args, **kwargs)
             else:
-                logger.debug(f'Class {cls.__name__} was loaded from persisted state successfully.')
+                logger.debug('Class %s was loaded from persisted state successfully.', cls.__name__)
                 was_loaded = True
 
             assert self.instance is not None
 
-            if (
-                    self.persist_at_shutdown is PersistAtShutdown.ALWAYS or
-                    (
-                        not was_loaded and
-                        self.persist_at_shutdown is PersistAtShutdown.IF_NOT_LOADED
-                    )
+            if self.persist_at_shutdown is PersistAtShutdown.ALWAYS or (
+                not was_loaded and self.persist_at_shutdown is PersistAtShutdown.IF_NOT_LOADED
             ):
                 logger.debug('Scheduling a deferred called to save at process shutdown time.')
                 atexit.register(self.instance.save)
             return self.instance
+
         return _load