backported the code to python 3.5 (and may be older) using futurize-fstrings

caching/cache.py

@@ -1,3 +1,4 @@
+# -*- coding: future_fstrings -*-
 import pickle
 from collections import OrderedDict
 from functools import wraps
@@ -65,14 +66,14 @@ def __init__(
                 results only in case of the exceptions are raisd in the
                 decorated function.
         """
-        self.params = OrderedDict(
-            maxsize=maxsize,
-            ttl=ttl,
-            filepath=filepath,
-            policy=policy,
-            key=key,
-            only_on_errors=only_on_errors,
-            **kwargs,
+        self.params = OrderedDict([
+            ('maxsize', maxsize),
+            ('ttl', ttl),
+            ('filepath', filepath),
+            ('policy', policy),
+            ('key', key),
+            ('only_on_errors', only_on_errors)] +
+            list(kwargs.items())
         )
         self.only_on_errors = only_on_errors
         self.make_key = key
@@ -84,10 +85,8 @@ def __init__(
         )
 
     def __repr__(self):
-        return (
-            f"{self.__class__.__name__}"
-            f"({', '.join(f'{k}={repr(v)}' for k,v in self.params.items())})"
-        )
+        param_str = ', '.join(f'{k}={repr(v)}' for k, v in self.params.items())
+        return f'{self.__class__.__name__}({param_str})'
 
     def _decorator(self, fn):
         if not callable(fn):

caching/storage.py

@@ -1,3 +1,4 @@
+# -*- coding: future_fstrings -*-
 import os
 import sqlite3
 from contextlib import suppress
@@ -92,10 +93,8 @@ def __repr__(self):
             (p, getattr(self, p))
             for p in ('filepath', 'maxsize', 'ttl')
         )
-        return (
-            f'{self.__class__.__name__}'
-            f"({', '.join(f'{k}={repr(v)}' for k,v in params)})"
-        )
+        param_str = ', '.join(f'{k}={repr(v)}' for k, v in params)
+        return f'{self.__class__.__name__}({param_str})'
 
     def __enter__(self):
         self.init_db()
@@ -152,11 +151,12 @@ def init_db(self):
             ''')
 
         with self.db as db:
+            addnl_col_str = ''.join(f"{c}, " for c in policy_stuff['additional_columns'])
             db.execute(f'''
                 CREATE TABLE IF NOT EXISTS cache (
                     key BINARY PRIMARY KEY,
                     ts REAL NOT NULL DEFAULT ({self.SQLITE_TIMESTAMP}),
-                    {''.join(f"{c}, " for c in policy_stuff['additional_columns'])}
+                    {addnl_col_str}
                     value BLOB NOT NULL
                 ) WITHOUT ROWID
             ''')

setup.py

@@ -55,9 +55,12 @@ def run_tests(self):
         'License :: OSI Approved :: MIT License',
         'Natural Language :: English',
         'Programming Language :: Python :: 3.6',
+        'Programming Language :: Python :: 3.5',
         'Programming Language :: Python :: Implementation :: CPython',
         'Programming Language :: Python :: Implementation :: PyPy',
     ],
+    install_requires=['future-fstrings'],
+    setup_requires=['future-fstrings'],
     tests_require=['pytest'],
     cmdclass={'test': PyTest},
 )

tests/test_cache.py

@@ -1,3 +1,4 @@
+# -*- coding: future_fstrings -*-
 import os
 import time
 

tests/test_storage_sqlite.py

@@ -1,3 +1,4 @@
+# -*- coding: future_fstrings -*-
 import os
 
 import pytest