From e8ba3dddeefe64ab533cbe3f82433fa9669c1370 Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Thu, 20 Nov 2025 06:32:37 +0000
Subject: [PATCH] Phase 1: Add CWP support to View initialization
Co-authored-by: tig <585482+tig@users.noreply.github.com>
---
Terminal.Gui/ViewBase/View.cs | 95 +++++++++++++++++++++++++++++++++--
1 file changed, 92 insertions(+), 3 deletions(-)
diff --git a/Terminal.Gui/ViewBase/View.cs b/Terminal.Gui/ViewBase/View.cs
index 68325dfe9..5dc0ad406 100644
--- a/Terminal.Gui/ViewBase/View.cs
+++ b/Terminal.Gui/ViewBase/View.cs
@@ -189,10 +189,34 @@ public partial class View : IDisposable, ISupportInitializeNotification
}
///
- /// Raised once when the is being initialized for the first time. Allows
- /// configurations and assignments to be performed before the being shown.
+ /// Raised during before initialization completes. Can be canceled by setting
+ /// to . Follows the Cancellable Work Pattern (CWP).
+ ///
+ ///
+ ///
+ /// This event is raised after the virtual method is called and before
+ /// the initialization work is performed. Subscribe to this event to perform pre-initialization work
+ /// or to cancel initialization.
+ ///
+ ///
+ /// This event follows Terminal.Gui's Cancellable Work Pattern. The pattern is:
+ /// 1. (pre-notification, can cancel)
+ /// 2. event (can cancel)
+ /// 3. Initialization work (sets = true, layouts, etc.)
+ /// 4. (post-notification)
+ /// 5. event
+ ///
+ ///
+ public event EventHandler? Initializing;
+
+ ///
+ /// Raised once when the has been initialized for the first time. Allows
+ /// configurations and assignments to be performed after the has been laid out.
/// View implements to allow for more sophisticated initialization.
///
+ ///
+ /// This is the post-notification event in the Cancellable Work Pattern pair with .
+ ///
public event EventHandler? Initialized;
///
@@ -254,7 +278,18 @@ public partial class View : IDisposable, ISupportInitializeNotification
/// Signals the View that initialization is ending. See .
///
- /// Initializes all SubViews and Invokes the event.
+ ///
+ /// Initializes all SubViews and invokes the event. Follows the Cancellable
+ /// Work Pattern (CWP).
+ ///
+ ///
+ /// The initialization flow is:
+ /// 1. (pre-notification, can cancel)
+ /// 2. event (can cancel)
+ /// 3. Initialization work (sets = true, layouts, etc.)
+ /// 4. (post-notification)
+ /// 5. event
+ ///
///
public virtual void EndInit ()
{
@@ -263,6 +298,22 @@ public partial class View : IDisposable, ISupportInitializeNotification
throw new InvalidOperationException ("The view is already initialized.");
}
+ // CWP Phase 1: Pre-notification via virtual method (can cancel)
+ if (OnInitializing ())
+ {
+ return; // Initialization canceled
+ }
+
+ // CWP Phase 2: Event notification (can cancel)
+ var args = new CancelEventArgs ();
+ Initializing?.Invoke (this, args);
+
+ if (args.Cancel)
+ {
+ return; // Initialization canceled
+ }
+
+ // CWP Phase 3: Perform initialization work
IsInitialized = true;
EndInitAdornments ();
@@ -290,9 +341,47 @@ public partial class View : IDisposable, ISupportInitializeNotification
// Thus, we call SetNeedsLayout() to ensure that the layout is performed at least once.
SetNeedsLayout ();
+ // CWP Phase 4: Post-notification via virtual method
+ OnInitialized ();
+
+ // CWP Phase 5: Post-notification event
Initialized?.Invoke (this, EventArgs.Empty);
}
+ ///
+ /// Called before the event and before initialization work is performed.
+ /// Override to provide custom pre-initialization logic or to cancel initialization.
+ ///
+ /// to cancel initialization; to proceed.
+ ///
+ ///
+ /// This is the first phase of the Cancellable Work Pattern (CWP) for view initialization.
+ /// Default implementation returns (allow initialization to proceed).
+ ///
+ ///
+ /// If this method returns , initialization is canceled, and neither the
+ /// event nor event will be raised.
+ ///
+ ///
+ protected virtual bool OnInitializing ()
+ {
+ return false; // Default: allow initialization
+ }
+
+ ///
+ /// Called after initialization work completes and before the event is raised.
+ /// Override to provide custom post-initialization logic.
+ ///
+ ///
+ /// This is the fourth phase of the Cancellable Work Pattern (CWP) for view initialization.
+ /// At this point, is , layout has been performed,
+ /// and all subviews have been initialized.
+ ///
+ protected virtual void OnInitialized ()
+ {
+ // Default: do nothing
+ }
+
#endregion Constructors and Initialization
#region Visibility