aspid-visual-element-fluent

aspid-visual-element-fluent

Use the fluent VisualElement extensions shipped by Aspid.FastTools to build UIToolkit trees with a single chained expression instead of multi-line imperative property setters.

When this skill applies

Trigger when the user:

• writes new UIToolkit code (editor windows, inspectors, runtime UI)
• modifies an existing VisualElement configuration with property assignments
• asks for "fluent" / "chainable" / "builder" UIToolkit code
• references style.X = Y, AddToClassList, RegisterValueChangedCallback, clicked +=, style.flexDirection = …, etc., where a fluent equivalent exists

Do not trigger for non-UIToolkit UI (uGUI, IMGUI), or for UXML/USS authoring (those have their own files). Mixed UXML + C# is fine — the C# part still uses these extensions.

Namespace

All extensions live in:

using Aspid.FastTools.UIElements;

Note: UIElements, not VisualElements. A common mistake is to assume the namespace mirrors the folder path — it does not.

Core convention

Every extension is generic in the receiver type:

public static T SetXxx<T>(this T element, …) where T : VisualElement
{
    // mutate
    return element;
}

The return type preserves the most-derived static type. So:

Button btn = new Button()
    .SetName("submit")          // returns Button (not VisualElement)
    .AddClicked(OnSubmit)       // Button-specific, only available because T is Button
    .SetWidth(120);             // returns Button

This means subtype-specific methods are available mid-chain as long as you start the chain with the subtype.

Catalog (by domain)

Identity & state — VisualElementExtensions

SetName, SetVisible, SetEnabled, SetTooltip, SetUserData, SetPickingMode, SetFocusable (where applicable), SetTabIndex.

USS classes & stylesheets — VisualElementExtensions.Uss

AddClass(string), RemoveClass(string), ToggleInClass(string), EnableInClass(string className, bool enable), ClearClasses(), AddStyleSheets(StyleSheet), RemoveStyleSheets(StyleSheet), AddStyleSheetsFromResource(string path), RemoveStyleSheetsFromResource(string path).