Add custom data class decorator that uses slots

novelwriter/types.py

@@ -23,6 +23,8 @@ along with this program. If not, see <https://www.gnu.org/licenses/>.
 """
 from __future__ import annotations
 
+from typing import Any, TypeVar
+
 from PyQt6.QtCore import Qt
 from PyQt6.QtGui import QColor, QFont, QPainter, QTextCharFormat, QTextCursor, QTextFormat
 from PyQt6.QtWidgets import QDialog, QDialogButtonBox, QHeaderView, QSizePolicy, QStyle
@@ -146,3 +148,30 @@ FONT_STYLE: dict[QFont.Style, str] = {
     QFont.Style.StyleItalic:  "italic",
     QFont.Style.StyleOblique: "oblique",
 }
+
+##
+#  Decorators and MetaClasses
+##
+
+T_ = TypeVar("T_", bound=object)
+
+
+def nwDataClass(cls: T_) -> T_:
+    """A simple data class decorator that generates slots automatically
+    and creates an init function to match.
+    """
+
+    def wrap(cls: T_) -> T_:
+        fields = tuple(a for a in dir(cls) if not a.startswith("__"))
+        values = {a: getattr(cls, a) for a in fields}
+
+        def init(self: Any) -> None:
+            nonlocal values
+            for a, v in values.items():
+                self.__setattr__(a, v)
+
+        return type(cls.__class__.__name__, (object,), {  # type: ignore
+            "__slots__": fields, "__init__": init
+        })
+
+    return wrap(cls)