apply __slots__ to resolver and reintroduce type conversations

freqtrade/strategy/resolver.py

@@ -21,6 +21,9 @@ class StrategyResolver(object):
     """
     This class contains all the logic to load custom strategy class
     """
+
+    __slots__ = ['strategy']
+
     def __init__(self, config: Optional[Dict] = None) -> None:
         """
         Load the custom class from config parameter
@@ -39,22 +42,24 @@ class StrategyResolver(object):
             logger.info("Override strategy \'minimal_roi\' with value in config file.")
 
         if 'stoploss' in config:
-            self.strategy.stoploss = float(config['stoploss'])
+            self.strategy.stoploss = config['stoploss']
             logger.info(
                 "Override strategy \'stoploss\' with value in config file: %s.", config['stoploss']
             )
 
         if 'ticker_interval' in config:
-            self.strategy.ticker_interval = int(config['ticker_interval'])
+            self.strategy.ticker_interval = config['ticker_interval']
             logger.info(
                 "Override strategy \'ticker_interval\' with value in config file: %s.",
                 config['ticker_interval']
             )
 
-        # Minimal ROI designed for the strategy
+        # Sort and apply type conversions
         self.strategy.minimal_roi = OrderedDict(sorted(
             {int(key): value for (key, value) in self.strategy.minimal_roi.items()}.items(),
-            key=lambda t: t[0]))  # sort after converting to number
+            key=lambda t: t[0]))
+        self.strategy.stoploss = float(self.strategy.stoploss)
+        self.strategy.ticker_interval = int(self.strategy.ticker_interval)
 
     def _load_strategy(self, strategy_name: str) -> Optional[IStrategy]:
         """
@@ -76,16 +81,12 @@ class StrategyResolver(object):
 
             raise ImportError('not found')
         # Fallback to the default strategy
-        except (ImportError, TypeError) as error:
-            logger.error(
+        except (ImportError, TypeError):
+            logger.exception(
                 "Impossible to load Strategy '%s'. This class does not exist"
                 " or contains Python code errors",
                 strategy_name
             )
-            logger.error(
-                "The error is:\n%s.",
-                error
-            )
             return None
 
     @staticmethod

freqtrade/tests/strategy/test_strategy.py

@@ -115,7 +115,6 @@ def test_strategy_override_ticker_interval(caplog):
 
 def test_strategy_fallback_default_strategy():
     strategy = StrategyResolver()
-    strategy.logger = logging.getLogger(__name__)
 
     assert not hasattr(StrategyResolver, 'custom_strategy')
     strategy._load_strategy('../../super_duper')