Flex and ui object initial settings - Chicken before egg?

[Phuket2]

@omz. Sorry in advance if this post is stupid. I am back to looking at flex attrs again. It's been some time since I was looking at these. But it seems to me there is a gap here in the logic. (Hmmm, cant believe I wrote that :) )
I have re-wrote this msg a few times as i am finding hard to explain.

I will try to explain:
Let's say I want prepare a ui.View that will have a height = 60 and be the width of its superview and be anchored to its x,y coord. So I want to be able to set the flex attr and the height of the view. But as far as the width goes I dont know what the width will be.
As far as I know this is not possible at the moment without using the layout method! I think that is correct. (Maybe I am wrong)
But If thats correct, would it make sense to have sentinel values for width and height like -1 to depict the superview's width/height. Maybe that's really bad form, maybe new attrs could be added for the elasticity of the width/height of a form.

Maybe I am in La La land again. But as far as I can tell/remember you cant fully define a views complete composition and elasticity without either first knowing its superview bounds or using the layout method. Would be nice if you could do this all ahead of time without any knowledge of the view or having to write a layout method. I guess that means more work for Pythonista under the hood.

But I personally find in the current system it's not quite there. Hence the chicken and egg reference. Getting a little late here now, Hope what I have written makes sense

[zrzka]

Not ideal, but you can do this (without layout):

from ui import *

class MyView(View):
    def __init__(self):
        self.background_color = 'white'
        
        yellow = View(background_color='yellow', flex='RBW')
        yellow.frame = (20, 20, self.width - 20, 60)
        self.add_subview(yellow)
        
v = MyView()
v.present('fullscreen')

[JonB]

One approach is to define everything based off a default width, then let present resize for you. I usually lazily do this:

root=ui.View() #for now, default is 0,0,100,100
v=ui.View(frame=(0, 0,root.width, 60))
v.flex='w' # height, x, and y are fixed, in absolute pixels
root.present() # will be resized