#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/money.py

@@ -79,7 +79,7 @@ def show_amount_from_pubkey(label, inputs_balance):
     totalAmountInput = inputs_balance[0]
     balance = inputs_balance[1]
     currency_symbol = get_currency_symbol()
-    ud_value = UDValue().ud_value
+    ud_value = get_ud_value()
     average, monetary_mass = get_average()
     member = False
 
@@ -184,23 +184,12 @@ def get_sources(pubkey):
     return listinput, amount
 
 
-class UDValue:
-    __instance = None
-
-    def __new__(cls):
-        if UDValue.__instance is None:
-            UDValue.__instance = object.__new__(cls)
-        return UDValue.__instance
-
-    def __init__(self):
-        self.ud_value = self.get_ud_value()
-
-    def get_ud_value(self):
-        client = ClientInstance().client
-        blockswithud = client(blockchain.ud)
-        NBlastUDblock = blockswithud["result"]["blocks"][-1]
-        lastUDblock = client(blockchain.block, NBlastUDblock)
-        return lastUDblock["dividend"] * 10 ** lastUDblock["unitbase"]
+def get_ud_value():
+    client = ClientInstance().client
+    blockswithud = client(blockchain.ud)
+    NBlastUDblock = blockswithud["result"]["blocks"][-1]
+    lastUDblock = client(blockchain.block, NBlastUDblock)
+    return lastUDblock["dividend"] * 10 ** lastUDblock["unitbase"]
 
 
 def amount_in_current_base(source):