itch.io

I believe I have resolved the problem; it will be patched in the next release, and modulo the typo correction I noted your example should work as intended.

As a general design note, I do not recommend directly exposing internal widgets of contraptions and banging on them from the outside; this is very brittle and makes it difficult to revise the design of the contraption or maintain internal constraints. Instead of exposing a slider via an attribute:

on get_slider do
 slider1
end

And then both updating the slider value and firing an event from the outside:

on click do
  s: prototype11.slider
  s.value: s.value + 1
  s.event["change" s.value + 1]
end

You could instead expose a function for incrementing the slider's value (and all the necessary consequences) on the contraption:

on get_inc do
  on inc do
   slider1.value:slider1.value + 1
   slider1.event["change" slider1.value + 1]
  end
end

And call it from the outside like so:

on click do
  prototype11.inc[]
end

Or, alternatively, you could expose both "get_"  and "set_" attributes on the contraption which likewise hide any side effects that are needed:

on get_v1 do
  slider1.value
end
on set_v1 x do
  slider1.value:x
  slider1.event["change" x]
end

And then from the outside it looks exactly like the read/write attributes of a primitive widget:

on click do
  prototype11.v1:prototype11.v1 + 1
end