unknown vars count about kiwi HOT 4 CLOSED

It can get fairly complex depending on how much of a "layout system" you want to build.

Here are the gritty details for how we generate constraints in Enaml:
https://github.com/nucleic/enaml/tree/master/enaml/layout

Those helpers are the "engine" which allow us to have things like vbox(*widgets):
https://github.com/nucleic/enaml/blob/master/enaml/widgets/v_group.py#L60-L61
https://github.com/nucleic/enaml/blob/master/enaml/layout/layout_helpers.py#L64
https://github.com/nucleic/enaml/blob/master/enaml/layout/linear_box_helper.py#L31

For your simple case exactly, you can use a simple sum:
solver.addConstraint(sum([item.width for item in items]) == parentWidth)

from kiwi.

Thanks. Sorry but can you explain how can i do this in c++?

from kiwi.

You could build an Expression of Terms and create a constraint where that expression is set to equal parentWidth.

In swift I would (pseudo)

let width0 = Variable()
let width1 = Variable()
let width2 = Variable()
let parentWidth = Variable()
let allWidths = Expression([Term(width0), Term(width1), Term(width2)])
let constraint = allWidths == parentWidth
solver.addConstraint(constraint)

from kiwi.

You can do like @hfossli said, using an std::vector of Term objects:
https://github.com/nucleic/kiwi/blob/master/kiwi/expression.h#L26

Or use a simple loop to accumulate the expression, but that will be more expensive due to the copy constructor on the vector being invoked for each term. One could make a case for some in-place operator overloads on Expression to make this easier/cheaper.

from kiwi.