From e99933b5200e0531025eb6fcfd2ed890624a6156 Mon Sep 17 00:00:00 2001
From: Alison Marczewski <alison.marczewski@gmail.com>
Date: Sun, 8 Mar 2020 16:58:07 -0300
Subject: [PATCH] Creating a callable param (hash_params) to generate key when
 positional and/or keywords arguments are not hashable. It can work as a
 workaround in scenarios that positional and keywords args are not hashable
 but one can be generated with a properly method for each case

---
 cachier/base_core.py   | 2 +-
 cachier/core.py        | 8 +++++++-
 cachier/mongo_core.py  | 4 ++--
 cachier/pickle_core.py | 4 ++--
 4 files changed, 12 insertions(+), 6 deletions(-)

diff --git a/cachier/base_core.py b/cachier/base_core.py
index 99b1d9a..6a9bb01 100644
--- a/cachier/base_core.py
+++ b/cachier/base_core.py
@@ -28,7 +28,7 @@ class _BaseCore():
         if such a mapping exists."""
 
     @abc.abstractmethod
-    def get_entry(self, args, kwds):
+    def get_entry(self, args, kwds, hash_params):
         """Returns the result mapped to the given arguments in this core's
         cache, if such a mapping exists."""
 
diff --git a/cachier/core.py b/cachier/core.py
index 793fe38..a909915 100644
--- a/cachier/core.py
+++ b/cachier/core.py
@@ -79,6 +79,7 @@ def cachier(
     pickle_reload=True,
     mongetter=None,
     cache_dir=None,
+    hash_params=None,
 ):
     """A persistent, stale-free memoization decorator.
 
@@ -112,6 +113,11 @@ def cachier(
         A fully qualified path to a file directory to be used for cache files.
         The running process must have running permissions to this folder. If
         not provided, a default directory at `~/.cachier/` is used.
+    hash_params : callable, optional
+        A callable that takes args and kwargs from main function and returns
+        a hash key of these params. If unset, default transformation is
+        applied. It is valuable and works as workaround in scenarios
+        that positional and keyword arguments are not hashable.
     """
     # print('Inside the wrapper maker')
     # print('mongetter={}'.format(mongetter))
@@ -142,7 +148,7 @@ def cachier(
                 _print = print
             if ignore_cache:
                 return func(*args, **kwds)
-            key, entry = core.get_entry(args, kwds)
+            key, entry = core.get_entry(args, kwds, hash_params)
             if overwrite_cache:
                 return _calc_entry(core, key, func, args, kwds)
             if entry is not None:  # pylint: disable=R0101
diff --git a/cachier/mongo_core.py b/cachier/mongo_core.py
index 2d2077d..e05b6da 100644
--- a/cachier/mongo_core.py
+++ b/cachier/mongo_core.py
@@ -79,8 +79,8 @@ class _MongoCore(_BaseCore):
             return key, entry
         return key, None
 
-    def get_entry(self, args, kwds):
-        key = pickle.dumps(args + tuple(sorted(kwds.items())))
+    def get_entry(self, args, kwds, hash_params):
+        key = pickle.dumps(args + tuple(sorted(kwds.items())) if hash_params is None else hash_params(args, kwds))
         return self.get_entry_by_key(key)
 
     def set_entry(self, key, func_res):
diff --git a/cachier/pickle_core.py b/cachier/pickle_core.py
index e6bdea0..fed5bb4 100644
--- a/cachier/pickle_core.py
+++ b/cachier/pickle_core.py
@@ -146,8 +146,8 @@ class _PickleCore(_BaseCore):
                 self._reload_cache()
             return key, self._get_cache().get(key, None)
 
-    def get_entry(self, args, kwds):
-        key = args + tuple(sorted(kwds.items()))
+    def get_entry(self, args, kwds, hash_params):
+        key = args + tuple(sorted(kwds.items())) if hash_params is None else hash_params(args, kwds)
         # print('key type={}, key={}'.format(type(key), key))
         return self.get_entry_by_key(key)