From 46a7f60460da7aa68884ba9ea75d5205ed252868 Mon Sep 17 00:00:00 2001
From: jan <jan@orange.mpxd.net>
Date: Fri, 7 Apr 2023 16:33:23 -0700
Subject: [PATCH] add @oneshot decorator

---
 masque/error.py            |  7 +++++++
 masque/utils/__init__.py   |  1 +
 masque/utils/decorators.py | 21 +++++++++++++++++++++
 3 files changed, 29 insertions(+)
 create mode 100644 masque/utils/decorators.py

diff --git a/masque/error.py b/masque/error.py
index 3bac722..0e46849 100644
--- a/masque/error.py
+++ b/masque/error.py
@@ -30,3 +30,10 @@ class PortError(MasqueError):
     Exception raised by builder-related functions
     """
     pass
+
+class OneShotError(MasqueError):
+    """
+    Exception raised when a function decorated with `@oneshot` is called more than once
+    """
+    def __init__(self, func_name: str) -> None:
+        Exception.__init__(self, f'Function "{func_name}" with @oneshot was called more than once')
diff --git a/masque/utils/__init__.py b/masque/utils/__init__.py
index 1e04a35..4df9f9a 100644
--- a/masque/utils/__init__.py
+++ b/masque/utils/__init__.py
@@ -5,6 +5,7 @@ from .types import layer_t, annotations_t, SupportsBool
 from .array import is_scalar
 from .autoslots import AutoSlots
 from .deferreddict import DeferredDict
+from .decorators import oneshot
 
 from .bitwise import get_bit, set_bit
 from .vertices import (
diff --git a/masque/utils/decorators.py b/masque/utils/decorators.py
new file mode 100644
index 0000000..c212cdd
--- /dev/null
+++ b/masque/utils/decorators.py
@@ -0,0 +1,21 @@
+from typing import Callable
+from functools import wraps
+
+from ..error import OneShotError
+
+
+def oneshot(func: Callable) -> Callable:
+    """
+    Raises a OneShotError if the decorated function is called more than once
+    """
+    expired = False
+
+    @wraps(func)
+    def wrapper(*args, **kwargs):
+        nonlocal expired
+        if expired:
+            raise OneShotError(func.__name__)
+        expired = True
+        return func(*args, **kwargs)
+
+    return wrapper