#397: Replace singletons with @functools.lru_cache() decorator

• Replace BlockchainParams() singleton with @functools.lru_cache()
• Replace HeadBlock() singleton with @functools.lru_cache()
• Replace UDValue() singleton with @functools.lru_cache()
• Replace CurrencySymbol() singleton with @functools.lru_cache()
• Replace ClientInstance() singleton with @functools.lru_cache()

Close #397 (closed).

silkaj/blockchain_tools.py

@@ -13,42 +13,25 @@
 # You should have received a copy of the GNU Affero General Public License
 # along with Silkaj. If not, see <https://www.gnu.org/licenses/>.
 
-from duniterpy.api.bma import blockchain
-
-from silkaj.network_tools import ClientInstance
-
-
-class BlockchainParams:
-    __instance = None
+import functools
 
-    def __new__(cls):
-        if BlockchainParams.__instance is None:
-            BlockchainParams.__instance = object.__new__(cls)
-        return BlockchainParams.__instance
-
-    def __init__(self):
-        self.params = self.get_params()
-
-    def get_params(self):
-        client = ClientInstance().client
-        return client(blockchain.parameters)
+from duniterpy.api.bma import blockchain
 
+from silkaj.network_tools import client_instance
 
-class HeadBlock:
-    __instance = None
 
-    def __new__(cls):
-        if HeadBlock.__instance is None:
-            HeadBlock.__instance = object.__new__(cls)
-        return HeadBlock.__instance
+@functools.lru_cache(maxsize=1)
+def get_blockchain_parameters():
+    client = client_instance()
+    return client(blockchain.parameters)
 
-    def __init__(self):
-        self.head_block = self.get_head()
 
-    def get_head(self):
-        client = ClientInstance().client
-        return client(blockchain.current)
+@functools.lru_cache(maxsize=1)
+def get_head_block():
+    client = client_instance()
+    return client(blockchain.current)
 
 
+@functools.lru_cache(maxsize=1)
 def get_currency():
-    return (HeadBlock().head_block)["currency"]
+    return get_head_block()["currency"]