Static factory methods for common layout configurations

[stefanuebe]

Describe your motivation

Currently, VerticalLayout and HorizontalLayout constructors behave in a certain way, that is not always useful. In the same time, they are often used multiple times as children of another component, where their default configuration is not suitable

• VerticalLayout comes with default padding, which leads to immense indents, when applied to every nested instance
• HorizontalLayout always aligns on top, which is not suitable, when used for input fields with labels plus buttons

The solution for that is, to instantiate the object, assign it to a local var, apply the changes (no padding, align centered or on baseline), but that always takes additional code, which seems like unnecessary boilerplate.

Describe the solution you'd like

Vertical- and horizontal layout should provide some common configuration methods, so that they can be used in an easier manner, without breaking existing code.

For instance:

VerticalLayout - all these come without padding (which should be documented)

• of(Components...) // simple alternative for the normal constructor
• stretched(Components...) // align-items: stretched
• centered(Components...) // align-items: centered (not sure if really a common case)

HorizontlLayout

• of(Components...) // not sure if needed, since the normal HorizontalLayout has no padding
• centered(Components...) // align-items: stretched)
• baselined(Components...) // align-items: baseline)

Describe alternatives you've considered

Creating my own "Components" factory class, but this is something, that needs to be repeated for every project or using some 3rd party addon, that provides a fluent api.

Additional context

No response

[yuriy-fix]

General idea sounds useful, would probably require a bit of API design.

[rolfsmeds]

Good idea, but wouldn't a fluent API make more sense for this, e.g.

var layout = new HorizontalLayout(a, b, c).withAlignItems(Alignment.BASELINE).withPadding(false);

Sure, it's a bit more code, but less weird. IIRC this is what Viritin has.

We could even provide multi-property withers like

var layout = new HorizontalLayout(a, b, c).withWhiteSpace(false);

which would disable both the default padding and spacing.

Another alternative would be static builder classes as proposed here.

[stefanuebe]

but wouldn't a fluent API make more sense for this

We had this topic a few times already internally and the main argument against fluent api was the idea of extendable components - which would make the fluent api then either unusable out of the box or would need additional generic parameters on classes or the component would need to override it with its own class as return type.

e.g.

public MyContainer extends VerticalLayout {
    public MyContainer withMyProperty(String s) {
        ...
        return this;
    }
}

add(new MyContainer()
    .withAlignItems(STRETCH)
    .withMyProperty("hello") // compiler error due to unknown method on VerticalLayout
);

I personally could totally live with this, since it is solvable by simply call the methods in correct order and we would finally have fluent api (which we already have at Grid Columns for instance).

And before this feature request dies again in a "fluent-or-not-fluent" discussion the simple static methods would be an easy to integrate tradeoff (despite some additional design of course) :)