Alternative compose

[willmcgugan]

I've added an alternative (and complimentary) way of composing widgets.

Building compose methods gets a little awkward at a certain level. Consider this method:

def compose(self) -> ComposeResult:
    yield Foo()
    yield Bar()
    yield Baz()

If I want to wrap that in a Horizontal, the syntax changes:

def compose(self) -> ComposeResult:
    yield Horizontal(    
        Foo(),
        Bar(),
        Baz(),
        id="wrapper"
    )

This change allows widgets to be used as a context manager, to introduce a new level.

def compose(self) -> ComposeResult:
    with Horizontal(id="wrapper"):
        yield Foo()
        yield Bar()
        yield Baz()

Both methods can coexist, but I find there are the following benefits with the context managers:

• It's easy to wrap something, add a line and indent the contents.
• The id and other parameters remain at the top.
• No need to add commas and braces.
• Adding many widgets doesn't require clumsy looking spat syntax Vertical(*[MyWidget() for _ in range(10)]).

This isn't documented yet. I've only changed internal apps for now. I want to see how we find this.

[davep]

Just from the description alone this gets an enthusiastic "oh hell yes!" from me.

[rodrigogiraoserrao]

I like this use of context managers!

[ofek]

Very nice!!!