[Enaml][py36]: subscription operator doesn't trigger 'visible' observer

Question

I am building a GUI that is separated in 3 columns, and in 1+ row.s. The number of row is decided by the user through an IntField.

Since every (displayed) row will contains plots, I don't want to detach them from the window in order to avoid recreating them. So I want to hide rows that aren't supposed to be displayed, keeping the already created, and attached, plots. I was thinking of the visible attribute of a container in order to do this.

Unfortunately the subscription doesn't seem to work on the visible field in my case.

Here is the code:

enamldef MyMenu(Container):
  attr context
  IntField:
    minimum = 1
    value := context.first_row
  IntField:
    minimum = 1
    value := context.last_row

enamldef MyPanel(Container):
  attr context
  Label:
    text << str(context.last_row - context.first_row)
    # subscription will work and label is updated
  Looper:
    iterable = range(35)
    Container:
      visible << loop_index <= context.last_row - context.first_row
      # visible won't update.
      # Only the init value of last_row and first_row will have an impact
      contraints = [height == 150]
      Label:
        text << str(context.last_sig - context.first_sig)
        # subscription will work and label is updated even in the loop & the container

Does anyone have an idea?

Answer 1

Hmmm, not sure why visible isn't working for you. It should be. I don't have time to debug it right now.

You could try using a Conditional object as the parent of the container:

enamldef MyPanel(Container):
  attr context
  Label:
    text << str(context.last_row - context.first_row)
  Looper:
    iterable = range(35)
    Conditional:
      condition << loop_index <= context.last_row - context.first_row
      Container:
        Label:
          text << str(context.last_sig - context.first_sig)