select formatter, docstring update

ytdl_subscribe/validators/base/string_formatter_validator.py

@@ -10,7 +10,6 @@ class StringFormatterValidator(StringValidator):
     Ensures user-created formatter strings are valid
     """
 
-    expected_value_type = str
     expected_value_type_name = "format string"
 
     FIELDS_VALIDATOR = re.compile(r"{([a-z_]+?)}")

ytdl_subscribe/validators/base/string_select_validator.py

@@ -0,0 +1,22 @@
+import re
+from keyword import iskeyword
+from typing import List
+from typing import Set
+
+from ytdl_subscribe.validators.base.validators import StringValidator
+
+
+class StringSelectValidator(StringValidator):
+    """
+    Ensures strings have selected one of the discrete allowed values.
+    """
+
+    select_values: Set[str] = set()
+
+    def __init__(self, name, format_string: str):
+        super().__init__(name=name, value=format_string)
+
+        if self.value not in self.select_values:
+            raise self._validation_exception(
+                f"Must be one of the following values: {', '.join(self.select_values)}"
+            )

ytdl_subscribe/validators/base/validators.py

@@ -9,10 +9,12 @@ from ytdl_subscribe.validators.exceptions import ValidationException
 
 class Validator:
     """
-    Abstract class used to validate any kind of field. Will ensure the value is the specified type.
+    Used to validate the value of a python object. This is the 'base' class that will first
+    check that the value's type matches the expected type. Validators that inherit from this should
+    perform their validation within the __init__.
     """
 
-    # The python type that value should be
+    # If the value is not this expected type, error
     expected_value_type: Type = object
 
     # When raising an error, call the type this value instead of its python name