Eliminate DocstringToMessage in errors

Author: rwb27

src/labthings_fastapi/exceptions.py

@@ -1,7 +1,5 @@
 """A submodule for custom LabThings-FastAPI Exceptions."""
 
-import inspect
-
 # The "import x as x" syntax means symbols are interpreted as being re-exported,
 # so they won't be flagged as unused by the linter.
 # An __all__ for this module is less than helpful, unless we have an
@@ -11,32 +9,7 @@
 )
 
 
-class DocstringToMessage:
-    """A mixin to put Exception docstrings in as their default message."""
-
-    append_to_message: bool = True
-
-    def __init__(self, message: str | None = None):
-        """Initialise an error with a message or its docstring.
-
-        :param message: the optional message.
-        """
-        # We ignore call-arg within this function because mypy can't know
-        # that this is a mixin, and super() will be an exception (which does
-        # accept a string argument to `__init__`).
-        doc = inspect.cleandoc(self.__doc__) if self.__doc__ else None
-        if message:
-            if doc and self.append_to_message:
-                super().__init__(message + "\n\n" + doc)  # type: ignore[call-arg]
-            else:
-                super().__init__(message)  # type: ignore[call-arg]
-        elif doc:
-            super().__init__(doc)  # type: ignore[call-arg]
-        else:
-            super().__init__()
-
-
-class NotConnectedToServerError(DocstringToMessage, RuntimeError):
+class NotConnectedToServerError(RuntimeError):
     """The Thing is not connected to a server.
 
     This exception is called if an Action is called or
@@ -46,7 +19,7 @@ class NotConnectedToServerError(DocstringToMessage, RuntimeError):
     """
 
 
-class ReadOnlyPropertyError(DocstringToMessage, AttributeError):
+class ReadOnlyPropertyError(AttributeError):
     """A property is read-only.
 
     No setter has been defined for this `.FunctionalProperty`, so

src/labthings_fastapi/thing_property.py

@@ -75,7 +75,6 @@ class attribute. Documentation is in strings immediately following the
 from .utilities.introspection import return_type
 from .base_descriptor import BaseDescriptor
 from .exceptions import (
-    DocstringToMessage,
     NotConnectedToServerError,
     ReadOnlyPropertyError,
 )
@@ -97,23 +96,23 @@ class attribute. Documentation is in strings immediately following the
 
 
 # The following exceptions are raised only when creating/setting up properties.
-class OverspecifiedDefaultError(DocstringToMessage, ValueError):
+class OverspecifiedDefaultError(ValueError):
     """The default value has been specified more than once.
 
     This error is raised when a `.DataProperty` is instantiated with both a
     ``default`` value and a ``default_factory`` provided.
     """
 
 
-class MissingDefaultError(DocstringToMessage, ValueError):
+class MissingDefaultError(ValueError):
     """The default value has not been specified.
 
     This error is raised when a `.DataProperty` is instantiated without a
     ``default`` value or a ``default_factory`` function.
     """
 
 
-class InconsistentTypeError(DocstringToMessage, TypeError):
+class InconsistentTypeError(TypeError):
     """Different type hints have been given for a property.
 
     Every property should have a type hint, which may be provided in a few
@@ -122,7 +121,7 @@ class InconsistentTypeError(DocstringToMessage, TypeError):
     """
 
 
-class MissingTypeError(DocstringToMessage, TypeError):
+class MissingTypeError(TypeError):
     """No type hints have been given for a property.
 
     Every property should have a type hint, which may be provided in a few