basic rings and storage

.gitignore

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+
+dist
+.env
+*.pyc
+*.egg-info
+MANIFEST
+
+.cache
+.eggs
+.idea
+.tox
+.ropeproject
+/build
+setup.cfg

cachain/ingredient.py

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+
+
+class Key(object):
+
+    def __init__(self, key):
+        self.key = key
+
+    def build(self, args):
+        raise NotImplementedError
+
+
+class FormatKey(Key):
+
+    def build(self, args):
+        return self.key.format(**args)
+
+
+class CallableKey(Key):
+
+    def build(self, args):
+        return self.key(**args)
+
+
+class Ring(object):
+
+    def __init__(self, storage, key):
+        self.storage = storage
+        if not isinstance(key, Key):
+            if isinstance(key, (str, unicode)):
+                key = FormatKey(key)
+            elif callable(key):
+                key = CallableKey(key)
+            else:
+                raise TypeError
+        self.key = key
+
+    @staticmethod
+    def _key_args(args, kwargs):
+        if args and kwargs:
+            raise TypeError
+        if args and len(args) > 1:
+            raise TypeError
+        if args:
+            key = args[0]
+        else:
+            key = kwargs
+        return key
+
+    def get(self, *args, **kwargs):
+        key_args = self._key_args(args, kwargs)
+        return self.get_by_key(key_args)
+
+    def get_by_key(self, key_args):
+        built_key = self.key.build(key_args)
+        return self.storage.get(built_key)
+
+    def set(self, _value, *args, **kwargs):
+        key_args = self._key_args(args, kwargs)
+        if callable(_value):
+            _value = _value(**key_args)
+        return self.set_by_key(_value, key_args)
+
+    def set_by_key(self, value, key_args):
+        built_key = self.key.build(key_args)
+        return self.storage.set(built_key, value)
+
+    def get_or_set(self, _value, *args, **kwargs):
+        key_args = self._key_args(args, kwargs)
+        value = self.get_by_key(key_args)
+        if value is None:
+            value = _value(**key_args)
+            self.set_by_key(value, key_args)
+        return value

cachain/storage.py

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+
+
+class Storage(object):
+
+    def get(self, key):
+        raise NotImplementedError
+
+    def set(self, key, value, expire=None):
+        raise NotImplementedError
+
+
+class DictStorage(Storage):
+
+    def __init__(self, storage):
+        self.storage = storage
+
+    def get(self, key):
+        return self.storage.get(key)
+
+    def set(self, key, value, expire=None):
+        assert expire is None, 'expire is not supported'
+        return self.storage.update({key: value})

tests/test_cachain.py

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+
+from cachain.storage import DictStorage
+from cachain.ingredient import Ring
+
+
+import pytest
+
+
+@pytest.fixture
+def fx_ring():
+    storage = DictStorage({})
+    ring = Ring(storage, 'user_id:{user_id}')
+    return ring
+
+
+def test_ring_get_set(fx_ring):
+    assert fx_ring.get({'user_id': 1}) is None
+    fx_ring.set(lambda user_id: 100, {'user_id': 1})
+
+
+def test_ring_get_or_set(fx_ring):
+    assert fx_ring.get({'user_id': 1}) is None
+    assert fx_ring.get_or_set(lambda user_id: 100, {'user_id': 1}) == 100
+    assert fx_ring.get({'user_id': 1}) == 100
+
+