Handle an explicit window-close event — Flash-check repair

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

Repair cancellation claims without inventing APIs

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.

A draft solution calls application.cancelEverything() on close and claims every native job stopped. The source supplies no such method and no cancellation acknowledgment semantics.

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: Replace the invented call with a required host contract: identify owned jobs, request cancellation through a documented mechanism if available, and define acknowledgment, late completion and partial artifact treatment. Until supplied, these remain design requirements.

Compare the tempting alternative: A plausible method name is not implementation evidence. Even a real cancellation request would not prove immediate termination without its documented guarantee.

Worked reasoning and supplied artifact

// Paper trace / supplied exercise-host contract; no execution claimed.
// A draft solution calls application.cancelEverything() on close and claims every native job stopped. The source supplies no such method and no cancellation acknowledgment semantics.
// Replace the invented call with a required host contract: identify owned jobs, request cancellation through a documented mechanism if available, and define acknowledgment, late completion and partial artifact treatment. Until supplied, these remain design requirements.

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 cancellation handshake for J8 using Requested, Acknowledged and Completed states, and identify the transition that cannot be claimed from the available source.

What to produce

A proposed handshake labeled unimplemented and an evidence-gap note.

• 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.

• Repair cancellation claims without inventing APIs
• Write a cancellation handshake for J8 using Requested, Acknowledged and Completed states, and identify the transition that cannot be claimed from the available source.
• Separate source-backed behavior, host requirements and untested predictions.

One small recap task

Rewrite one cancellation claim as an explicit host requirement.

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