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Comment by CharlieDigital | Hacker News Reader

   > A class Rectangle can be pretty much whatever you want

In what way can an `HTMLDivElement` not emulate a `class Rectangle`?

    - Both are rectilinear
    - Both have width, height
    - Both can have borders, backgrounds
    - Both can be positioned in various grid/layout systems
    - Both can contain child instances
    - Both can contain a variety of child nodes like `Text`
    - Both can be clipped and masked
    - Both can be layered

What can you do with a `class Rectangle` from a GUI perspective that you can't do with an `HTMLDivElement`?

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A class Rectangle can be whatever you want. You can overload it. You can change everything including how it’s rendered. It doesn’t have to be any of the things you list.

A div element is a node in a tree which will be rendered by your browser in the way specified by the spec. You absolutely can’t freely do most of the actions you list to a div. There are severe limitations.

A div doesn’t at all emulate a class. Its semantically something completely different.

    > A Rectangle component is a node in a component tree which will be rendered by your OS graphics library in the way specified by the spec. You absolutely can’t freely do most of the actions you list to a div. There are severe limitations.

No?

It seems like you're just talking about a `Rectangle` in the abstract rather than the real limitation that even `class Rectangle` is subject to the rules of the runtime engine that renders said `Rectangle`...in a component tree...with the restrictions of the OS/GUI framework...

> No?

No.

Rendering outside of a web browser gives you a lot more freedom when it comes to how you layout and render. Rendering engines don’t necessarily use components tree by the way.

Even gui frameworks (which is what I think you are talking about with OS graphic library) have layout engines which are a lot more powerful than css. Flexbox is a step in the right direction but still inferior to what some frameworks could do 20 years ago.

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