Pre-commit rates.py

Author: Joaopeuko

mqpy/rates.py

@@ -1,19 +1,18 @@
 """Module for retrieving and managing historical price data from MetaTrader 5.
+
 Provides the Rates class for accessing historical price information.
 """
 
 from __future__ import annotations
 
-from typing import Union
-
 import MetaTrader5 as Mt5
 
 
 class Rates:
     """Represents historical price data for a financial instrument."""
 
     def __init__(self, symbol: str, time_frame: int, start_position: int, count: int) -> None:
-        """Initialize a Rates object.
+        """Initializes a Rates object.
 
         Args:
             symbol (str): The financial instrument symbol.
@@ -24,15 +23,14 @@ def __init__(self, symbol: str, time_frame: int, start_position: int, count: int
         Returns:
             None
         """
-        self._symbol = symbol
-        self._time_frame = time_frame
-        self._start_position = start_position
-        self._count = count
+
+        def _raise_value_error(msg: str) -> None:
+            raise ValueError(msg)
 
         try:
             rates = Mt5.copy_rates_from_pos(symbol, time_frame, start_position, count)
             if rates is None:
-                raise ValueError(f"Failed to retrieve rates for {symbol}")
+                _raise_value_error(f"Failed to retrieve rates for {symbol}")
 
             self._time = [rate[0] for rate in rates]
             self._open = [rate[1] for rate in rates]
@@ -42,11 +40,11 @@ def __init__(self, symbol: str, time_frame: int, start_position: int, count: int
             self._tick_volume = [rate[5] for rate in rates]
             self._spread = [rate[6] for rate in rates]
             self._real_volume = [rate[7] for rate in rates]
-        except Exception as e:
-            raise ValueError(f"Failed to create Rates object for symbol {symbol}. Error: {e}")
+        except Mt5.Error as e:
+            raise ValueError(f"Failed to create Rates object for symbol {symbol}") from e
 
     @property
-    def time(self) -> list[Union[int, float]]:
+    def time(self) -> list[int | float]:
         """List of timestamps."""
         return self._time