From 9c6b4d50b83886b828d4bf167cc0da4e5aa7cc4e Mon Sep 17 00:00:00 2001
From: Russell Keith-Magee <russell@keith-magee.com>
Date: Mon, 19 Jun 2023 06:49:18 +0800
Subject: [PATCH] Improve error message when a platform doesn't support a
 widget.

---
 android/src/toga_android/factory.py   | 4 ++++
 changes/1992.feature.rst              | 1 +
 cocoa/src/toga_cocoa/factory.py       | 4 ++++
 gtk/src/toga_gtk/factory.py           | 4 ++++
 iOS/src/toga_iOS/factory.py           | 4 ++++
 web/src/toga_web/factory.py           | 4 ++++
 winforms/src/toga_winforms/factory.py | 4 ++++
 7 files changed, 25 insertions(+)
 create mode 100644 changes/1992.feature.rst

diff --git a/android/src/toga_android/factory.py b/android/src/toga_android/factory.py
index 3f5d6fecce..fd664dd5f3 100644
--- a/android/src/toga_android/factory.py
+++ b/android/src/toga_android/factory.py
@@ -62,3 +62,7 @@ def not_implemented(feature):
     "Paths",
     "dialogs",
 ]
+
+
+def __getattr__(name):  # pragma: no cover
+    raise NotImplementedError(f"Toga's Android backend doesn't implement {name}")
diff --git a/changes/1992.feature.rst b/changes/1992.feature.rst
new file mode 100644
index 0000000000..803d761478
--- /dev/null
+++ b/changes/1992.feature.rst
@@ -0,0 +1 @@
+A more informative error message is returned when a platform backend doesn't support a widget.
diff --git a/cocoa/src/toga_cocoa/factory.py b/cocoa/src/toga_cocoa/factory.py
index c16e2ab0e6..cda6b628d1 100644
--- a/cocoa/src/toga_cocoa/factory.py
+++ b/cocoa/src/toga_cocoa/factory.py
@@ -77,3 +77,7 @@ def not_implemented(feature):
     "WebView",
     "Window",
 ]
+
+
+def __getattr__(name):  # pragma: no cover
+    raise NotImplementedError(f"Toga's Cocoa backend doesn't implement {name}")
diff --git a/gtk/src/toga_gtk/factory.py b/gtk/src/toga_gtk/factory.py
index ad4d0ce0a0..5e0694f300 100644
--- a/gtk/src/toga_gtk/factory.py
+++ b/gtk/src/toga_gtk/factory.py
@@ -73,3 +73,7 @@ def not_implemented(feature):
     "WebView",
     "Window",
 ]
+
+
+def __getattr__(name):  # pragma: no cover
+    raise NotImplementedError(f"Toga's GTK backend doesn't implement {name}")
diff --git a/iOS/src/toga_iOS/factory.py b/iOS/src/toga_iOS/factory.py
index 53278a1971..eba2cd9347 100644
--- a/iOS/src/toga_iOS/factory.py
+++ b/iOS/src/toga_iOS/factory.py
@@ -72,3 +72,7 @@ def not_implemented(feature):
     "WebView",
     "Window",
 ]
+
+
+def __getattr__(name):  # pragma: no cover
+    raise NotImplementedError(f"Toga's iOS backend doesn't implement {name}")
diff --git a/web/src/toga_web/factory.py b/web/src/toga_web/factory.py
index d563f14993..be253f674f 100644
--- a/web/src/toga_web/factory.py
+++ b/web/src/toga_web/factory.py
@@ -75,3 +75,7 @@ def not_implemented(feature):
     # 'WebView',
     # 'Window',
 ]
+
+
+def __getattr__(name):  # pragma: no cover
+    raise NotImplementedError(f"Toga's Web backend doesn't implement {name}")
diff --git a/winforms/src/toga_winforms/factory.py b/winforms/src/toga_winforms/factory.py
index 52eee11c08..b50675cd29 100644
--- a/winforms/src/toga_winforms/factory.py
+++ b/winforms/src/toga_winforms/factory.py
@@ -72,3 +72,7 @@ def not_implemented(feature):
     "WebView",
     "Window",
 ]
+
+
+def __getattr__(name):  # pragma: no cover
+    raise NotImplementedError(f"Toga's Winforms backend doesn't implement {name}")