Add in-memory support.

fastapi_cache/__init__.py

@@ -1,11 +1,17 @@
 class FastAPICache:
     _backend = None
     _prefix = None
+    _expire = None
+    _init = False
 
     @classmethod
-    def init(cls, backend, prefix: str = ""):
+    def init(cls, backend, prefix: str = "", expire: int = None):
+        if cls._init:
+            return
+        cls._init = True
         cls._backend = backend
         cls._prefix = prefix
+        cls._expire = expire
 
     @classmethod
     def get_backend(cls):
@@ -14,5 +20,8 @@ class FastAPICache:
 
     @classmethod
     def get_prefix(cls):
-        assert cls._prefix, "You must call init first!"  # nosec: B101
         return cls._prefix
+
+    @classmethod
+    def get_expire(cls):
+        return cls._expire