Allow layout to be a list of components.

[T4rk1n]

Add the ability to set the layout as a list of components.

Example:

from dash import html, dcc, Input, Output, Dash

app = Dash()

app.layout = [
    html.Div("one", id="one"),
    html.Div("two", id="two"),
]

[AnnMarieW]

Just curious about the purpose of this PR.
So all this does is to make it unnecessary to use html.Div( ) as the container of app.layout? What's the advantage?

[T4rk1n]

@AnnMarieW

So all this does is to make it unnecessary to use html.Div( ) as the container of app.layout?

Yes that is all it does, reduce the number of characters and remove a mostly useless div in many cases. 🙂

[ndrezn]

The main advantage is that we can make a lot of our introductory documentation easier to understand for folks with a Python background but with no HTML background.

[AnnMarieW]

To me, it seems like it's just another rule to learn. You need to use a component everywhere except with top level of app.layout? You can't get too far in dash with using html components.

[alexcjohnson]

You can also think of it as changing from one existing rule to another - now layout looks like a children prop

[ndrezn]

Although I see @AnnMarieW 's point as a "new rule" I think generally this introduces better parity with children, and to me more importantly means that the "Hello World!" Dash examples do not require html.Div but require instead the far more understandable Python list -- ofc you can always do it the traditional way but it'll be a nice simplication of our early docs that I expect won't take much away in terms of pedagogy (hopefully soon we can come to a place where Dash devs don't need to learn HTML concepts to build cool projects!).

Nice work Phillipe and nice test as well! 💃