fix(cache): support for unpassed default args (#39)

* feat(cache): support caching functions with positional-only arguments

BREAKING CHANGE: requires Python version >= 3.8

* fix(cache): cache params with defaults not passed as args

---------

Co-authored-by: Taylor Hakes <[email protected]>

redis_cache/__init__.py

@@ -1,7 +1,7 @@
 from functools import wraps
 from json import dumps, loads
 from base64 import b64encode
-from inspect import signature
+from inspect import signature, Parameter
 
 def compact_dump(value):
     return dumps(value, separators=(',', ':'), sort_keys=True)
@@ -44,6 +44,10 @@ def get_args(fn, args, kwargs):
                     parsed_args[vkwargs_name] = {}
                 parsed_args[vkwargs_name][key] = value
 
+    for param in arg_sig.parameters.values():
+        if param.name not in parsed_args and param.default is not Parameter.empty:
+            parsed_args[param.name] = param.default
+
     return parsed_args
 
 

tests/test_redis_cache.py

@@ -365,6 +365,9 @@ def fn5(*, d, **e):
     def fn6(a, b, /, c, d):
         pass
 
+    def fn7(a, b, c=3, *, d):
+        pass
+
     assert get_args(fn1, (1,2), {}) == dict(a=1, b=2)
     assert get_args(fn1, [], dict(a=1, b=2)) == dict(a=1, b=2)
     assert get_args(fn1, [1], dict(b=2)) == dict(a=1, b=2)
@@ -373,6 +376,7 @@ def fn6(a, b, /, c, d):
     assert get_args(fn4, [1, 2, 3, 4], dict(d=5, f=6, g=7, h=8)) == dict(a=1, c=[2, 3, 4], d=5, e=dict(f=6, g=7, h=8))
     assert get_args(fn5, [], dict(d=5, f=6, g=7, h=8)) == dict(d=5, e=dict(f=6, g=7, h=8))
     assert get_args(fn6, [1, 2, 3], dict(d=4)) == dict(a=1, b=2, c=3, d=4)
+    assert get_args(fn7, [1, 2], dict(d=4)) == dict(a=1, b=2, c=3, d=4)
 
 # Simulate the environment where redis is not available
 # Only test the CacheDecorator since the exception handling should be done inside the decorator