add refactoring to fix linter errors

snap7/util.py

@@ -556,8 +556,10 @@ def get_string(bytearray_: bytearray, byte_index: int) -> str:
     if str_length > max_string_size or max_string_size > 254:
         logger.error("The string is too big for the size encountered in specification")
         logger.error("WRONG SIZED STRING ENCOUNTERED")
-        raise TypeError("String contains {} chars, but max. {} chars are expected or is larger than 254."
-                        "Bytearray doesn't seem to be a valid string.".format(str_length, max_string_size))
+        raise TypeError(
+            f"String contains {str_length} chars, but max. {max_string_size} chars are expected or is larger than 254."
+            "Bytearray doesn't seem to be a valid string."
+        )
     data = map(chr, bytearray_[byte_index + 2:byte_index + 2 + str_length])
     return "".join(data)
 
@@ -1783,19 +1785,11 @@ def set_value(self, byte_index: Union[str, int], type_: str, value: Union[bool,
         byte_index = self.get_offset(byte_index)
 
         if type_.startswith('FSTRING') and isinstance(value, str):
-            max_size = re.search(r'\d+', type_)
-            if max_size is None:
-                raise ValueError("Max size could not be determinate. re.search() returned None")
-            max_size_grouped = max_size.group(0)
-            max_size_int = int(max_size_grouped)
+            max_size_int = self._get_max_size(type_)
             return set_fstring(bytearray_, byte_index, value, max_size_int)
 
         if type_.startswith('STRING') and isinstance(value, str):
-            max_size = re.search(r'\d+', type_)
-            if max_size is None:
-                raise ValueError("Max size could not be determinate. re.search() returned None")
-            max_size_grouped = max_size.group(0)
-            max_size_int = int(max_size_grouped)
+            max_size_int = self._get_max_size(type_)
             return set_string(bytearray_, byte_index, value, max_size_int)
 
         if type_ == 'REAL':
@@ -1878,3 +1872,12 @@ def read(self, client: Client) -> None:
         # replace data in bytearray
         for i, b in enumerate(bytearray_):
             data[i + self.db_offset] = b
+
+    def _get_max_size(self, type_: str) -> int:
+        max_size = re.search(r"\d+", type_)
+        if max_size is None:
+            raise ValueError(
+                "Max size could not be determinate. re.search() returned None"
+            )
+        max_size_grouped = max_size.group(0)
+        return int(max_size_grouped)