setPadding of FlowRowsLayout not working

ccpplinux

Hi,
As per code given on the page https://feathersui.com/learn/haxe-openfl/flow-rows-layout/ when I am trying to use the code layout.setPadding(10.0); then I am getting following error message:

feathers.layout.ILayout has no field setPadding

Can any one help me to fix this error message. Here is my code:

import feathers.controls.Application;
import feathers.controls.Label;
import feathers.controls.LayoutGroup;
import feathers.controls.Button;
import feathers.layout.FlowRowsLayout;

class FlowRowsLayoutTest extends Application 
{
	public function new() 
	{
		super();

		var container = new LayoutGroup();
		
		var child1 = new Button();
		child1.text = "One";
		container.addChild(child1);
		
		var child2 = new Button();
		child2.text = "Two";
		container.addChild(child2);
		
		var child3 = new Button();
		child3.text = "Three";
		container.addChild(child3);

		container.layout = new FlowRowsLayout();

		container.layout.setPadding(10.0);

		addChild(container);
	}
}

joshtynjala

ccpplinux feathers.layout.ILayout has no field setPadding
container.layout.setPadding(10.0);

The layout property is typed ILayout, which doesn't define a setPadding() method. The setPadding() method is defined on FlowRowsLayout. So you need to cast it to the correct type to call that method.

cast(container.layout, FlowRowsLayout).setPadding(10.0);

ccpplinux

Thanks. It is working now. But when container.layout is already an object of the class FlowRowsLayout and so why there is need it to typecast to FlowRowsLayout?

joshtynjala

ccpplinux The compiler knows only that container.layout is of type ILayout. You could pass a different layout to container.layout later, such as HorizontalLayout or VerticalLayout. Then, it wouldn't be FlowRowsLayout anymore.

Admittedly, in your code above, it's very unlikely that the layout would somehow change between the line with new FlowRowsLayout() and the next line with setPadding(). However, in a more complex situation, where there are additional lines in between those two, the compiler would have a very difficult time determining which layout is in use. It would need to actually run your code to know for sure, which isn't really something a compiler is supposed to do.

I usually try to set properties on the layout before I pass it to the container, like this:

var containerLayout = new FlowRowsLayout();
containerLayout.setPadding(10.0);
container.layout = containerLayout;

In this style, no casting is needed.

ccpplinux

Thanks for clarification. I like your following approach:

joshtynjala var containerLayout = new FlowRowsLayout();
containerLayout.setPadding(10.0);
container.layout = containerLayout;