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Op 7 aug. 2014 11:35 schreef Simon Cozens <simon@simon-cozens.org>:
>
> Hello!
>
> I have just released my first luarock, a port of the UW Cassowary Constraint
> Solving Toolkit. Hopefully I got everything right...
Congratulations!
>
> Cassowary is "an incremental constraint solving toolkit that efficiently
> solves systems of linear equalities and inequalities." Basically, it solves
> equations for you. This is incredibly useful in UI work, when you might want
> widget A to be twice the width of widget B but the total width of A and B to
> be not more than 500 pixels; this is why Apple uses it to lay out the UI of OS
> X applications.
>
> Here's an example:
>
> cassowary = require("cassowary")
>
> -- Create a new solver object
> local solver = cassowary.SimplexSolver();
>
> -- Create lua variables to represent x and y
> local x = cassowary.Variable({ name = 'x' });
> local y = cassowary.Variable({ name = 'y' });
>
> -- Let's encode some expressions:
>
> -- x < y
> solver:addConstraint(cassowary.Inequality(x, "<=", y))
>
> -- y = x + 3
> solver:addConstraint(cassowary.Equation(y, cassowary.plus(x, 3)))
>
> -- either x = 10 or y = 10
> solver:addConstraint(cassowary.Equation(x, 10, cassowary.Strength.weak))
> solver:addConstraint(cassowary.Equation(y, 10, cassowary.Strength.weak))
>
> -- The solver automatically tries to resolve the current situation
> -- whenever constraints are added, so all we need to do is look
> -- at the values:
>
> print("x = "..x.value)
> print("y = "..y.value)
>
> Depending on the phase of the moon, you will either see:
>
> x=7
> y=10
>
> or
>
> x=10
> y=13
>
>
> This port is itself a port of the _javascript_ port at
> https://github.com/slightlyoff/cassowary.js but any errors are almost
> certainly my responsibility. (Not that I understand what the code is doing,
> I'm just mindlessly translating the language.)
>
> I'll be using it to improve the way that text frames are declared in my SILE
> typesetting engine ( https://github.com/simoncozens/sile ) but I hope it's
> useful to others as well. I'm sure those embedding lua into games can find
> interesting uses for it. Anyway, have fun.
>
> Simon
>
I noticed that the module depends on stdlib, for only an object system and some table operations. Any chance of removing that dependency? I try to make most of my modules indepedent, especially from the larger modules. (also because I tend to use penlight, not stdlib)
But nice work anyway!
Thijs