Handle an explicit window-close event — Build the smallest useful slice

PART I

Warm-up

Reconnect with a useful idea before starting handle an explicit window-close event. In one or two sentences, describe the input, output or host boundary from the previous exercise that this lesson builds on. If you are arriving directly, skim the worked example first; there is no locked prerequisite.

A rough note is enough. You can revise it after the example.

PART II

Instruction & guided example

Build a close response that retains a draft

Closing a window ends an owner, not all work everywhere. A window-close event is a host lifecycle signal. The source leaves cancellation methods and exact late-result rules unresolved, so use an explicit exercise contract. Closing one owner must not silently cancel another owner or grant a late callback permission to update an unrelated screen.

The draft owner is window W4. Exercise policy: confirmed close retains the draft in host-managed draft storage for 24 hours. No storage method signature is supplied. Retention confirmation arrives before close confirmation.

Track window identity, operation identity, dirty local work, and delivery time. Distinguish the user requesting close from the host confirming close. Whether close may be delayed, whether a draft is retained, and who completes cleanup are contract decisions. Worked case: Request retention → receive confirmation for W4’s draft → permit confirmed close. After close the window is gone but the retained draft remains under its own policy. Window lifetime and retained-data lifetime differ.

Compare the tempting alternative: Deleting every resource when a window closes violates the explicit retention promise; keeping the entire live window is not necessary to retain the draft.

Worked reasoning and supplied artifact

// Paper trace / supplied exercise-host contract; no execution claimed.
// The draft owner is window W4. Exercise policy: confirmed close retains the draft in host-managed draft storage for 24 hours. No storage method signature is supplied. Retention confirmation arrives before close confirmation.
// Request retention → receive confirmation for W4’s draft → permit confirmed close. After close the window is gone but the retained draft remains under its own policy. Window lifetime and retained-data lifetime differ.

Illustrative example from the proposed WillowScript design. The language and WUIX/WMATH/WDB/WAUDIO/WTMP services are not implemented in the supplied source. This site has no interpreter, VM or native host and does not execute or certify the snippet.

Try the guided change

Reconstruct the supplied worked case first: list its inputs, intermediate decisions and final artifact. Compare each row with the explanation and identify exactly where the rejected alternative fails. Then use the changed inputs in Part IV for independent work.

• Write the supplied inputs and initial state before following the example.
• Reconstruct each intermediate calculation or host decision, then compare with the worked artifact.
• Explain why the contrasting alternative fails before attempting the changed inputs in Part IV.

PART III

Take a breather

Step back after the guided example. Look away from the screen, stretch, or reread your prediction. This is an optional learning pause, not a timer or an assessment gate.

When you return, try to name the lesson’s key idea without copying its wording. If that feels difficult, return to Part II and trace one line rather than restarting the entire lesson.

PART IV

Independent practice

Project context: Support request workflow. Build a small, understandable change around handle an explicit window-close event.

Write a lifecycle contract naming window owner, retained draft owner, quota and expiry, then trace retention failure.

What to produce

A two-owner lifecycle diagram and a close-precondition table.

• State the intended behavior in a sentence before editing.
• Use only source-backed syntax and the host services whose contract you have been given.
• Record a normal case and a boundary or unavailable-resource case.
• Label hand predictions separately from anything actually measured in a supplied toolchain.

Syntax colors are a reading aid, not a compiler. The line you are editing stays uncolored until you move to a different line; capitalization is never changed. Drafts stay on this browser and code is not executed.

import wuix.widget;
import app;
domain Workspace {
    const application = Application({
        name: "Workspace",
        window: { title: "Dashboard", size: [1280, 800] },
        events: {
            "app.ready": fnc() -> void { console.log("Ready"); }
        }
    });
}

PART V

Self-check

Use this check to notice what to revisit. It does not award a private course grade, block another page or claim to verify compiled code. Every answer has a learning explanation.

You may keep exploring even if you are unsure. Use the hint, compare the trace, and revise your explanation.

PART VI

Recap & small task

Bring the idea back to the mod feature you are building. A useful recap connects the mechanism to a decision you can make in your own code.

• Build a close response that retains a draft
• Write a lifecycle contract naming window owner, retained draft owner, quota and expiry, then trace retention failure.
• Separate source-backed behavior, host requirements and untested predictions.

One small recap task

Write the retained draft’s expiry rule in plain words.

This marks your personal practice record only. It is not a certification or an official workspace assessment.