amoeba | Cassowary constraint solving algorithm implements in pure C

I am new to SpriteKit, and I am trying to create a distorted circle that acts like "amoeba". What I am trying to do is to use SKShapeNode initialised with with UIBezierPath created over 8-10 points on a circle with some randomness (something like):

In the following script, I declare and modify @basearray in the main program. Inside the dosomething subroutine, I access @basearray, assign it to an array local to the script, and modify the local copy. Because I have been careful to change the value only of local variables inside the subroutine, @basearray is not changed.

If I had made the mistake of assigning a value to @basearray inside the subroutine, though, it would have been changed and that value would have persisted after the call to the subroutine.

This is demonstrated in the 2nd subroutine, doagain.

Also, doagain receives the reference \@basearray as an argument rather than accessing @basearray directly. But going to that additional trouble provides no additional safety. Why do it that way at all?

Is there a way to guarantee that I cannot inadvertently change @basearray inside any subroutine? Any kind of hard safety device that I can build into my code, analogous to use strict;, some combination perhaps of my and local?

Am I correct in thinking that the answer is No, and that the only solution is to not make careless programmer errors?

When hitting the submit button on my form in form.html.erb, it is not submitting, and I get a message saying 'Please review the problems below:' but it doesn't list any problems.

Can anyone please explain to me why this is happening, and how I can fix it? It would be much appreciated.

schedule.rb