Compose text and button components — Flash-check repair

PART I

Warm-up

Reconnect with a useful idea before starting compose text and button components. 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 a callback signature mismatch

Text communicates state and a button requests an action. Their composition needs a semantic contract: label, event, target, permission, repeated action and failure response. Native controls do not remove those responsibilities. Callback values and object configuration are proposed source forms, not executed code here.

Host contract: click invokes fnc() -> void with no arguments. A draft callback declares an Event parameter and reads event.productId. No Event payload or productId field is supplied for this control.

Worked reasoning: The draft requires input the host does not deliver. A repair may use a no-argument response and a separately supplied selected-product value, or request a different documented event contract. Renaming the parameter does not create the missing payload.

Failed alternative: Inventing event.productId silently adds both a host argument and a field, so it cannot be justified by callback syntax.

Worked reasoning and supplied artifact

Host delivery:click() ->void
Draft expectation:click(Event with productId) ->void
Mismatch:one undeclared argument plus undeclared field
Repair contract:no-arg response reads explicitly supplied selectedId42

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: Operations dashboard. Build a small, understandable change around compose text and button components.

Review a no-argument Confirm control whose draft reads event.quantity. Specify the missing dependency and a correct supplied-input alternative.

What to produce

A host-versus-handler signature comparison and repaired response contract.

• 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.button;
import wuix.layout;
domain Login {
    const screen = {
        layout: { type: "column", padding: [24, 32], gap: 16 },
        components: [{ type: "text", value: "Welcome back" }]
    };
    fnc show() -> void {
        wuix.mount("main", screen);
    }
}

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 a callback signature mismatch
• Review a no-argument Confirm control whose draft reads event.quantity. Specify the missing dependency and a correct supplied-input alternative.
• Separate source-backed behavior, host requirements and untested predictions.

One small recap task

List delivered arguments before reading any callback parameter.

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