I hope that examples like this, and nophead's, will make it into some documentation, so that people do not have to reinvent the wheel. Jon On 9/7/2016 9:07 AM, Ronaldo wrote: > Counting ocurrences of some event was one of the first astonishing task stuck > me in my first steps in OpenSCAD when I found that variables are immutable. > I finally arrived to this non recursive solution: > > len( [ for(element=list) if(event_predicate(element)) 1] ) > > For the problem of finding the first ocurrence of an event, you always can > do: > > [ for(element=list) if(event_predicate(element)) element ][0] > > Another surprising task was to add up the elements of a list. Now I have a > bunch of solutions to that. > Besides given better name to what is called now variables, it is important > to ilustrate the techniques for common tasks like those in the manual. > >

+1 for parameters. please also consider that - besides in loops - its useful to have changeable variables for those of us who want to use random sequences with seeds for procedural variations in the design. This is hard to control right now.

Neon22 wrote > please also consider that - besides in loops - its useful to have > changeable variables for those of us who want to use random sequences > with seeds for procedural variations in the design. I don't believe that will help you. The language is defined such that every procedure call is determinate. Therefore the result of calling your Random() function can be assumed to be constant and so it only needs to be called once. Even if it does get called every time you want it to be, you can never predict the order in which each instance is called. It's messy, but it can be done. Here's one way. 1. create a file containing a million random numbers and read them into your open SCAD program. 2. calculate how many random numbers every one of your functions will consume. Or, in the difficult cases, the maximum number. Probably make variables to keep that information. 3. Give each function an argument specifying the base index to use for its random numbers. 4. Your Random function has a single argument giving the index into the million numbers that it should use. So for example if B() used two numbers and C() used three, then A(), which called B and C would use five. It would call B with a base index the same as the base index it was given, and then it would call C with the base index plus two. -- View this message in context: http://forum.openscad.org/What-to-call-variables-tp18260p18344.html Sent from the OpenSCAD mailing list archive at Nabble.com.

How about for starters, we deprecate the ability to reassign. In the GUI, so command line -D is OK. That will make it clear that such usage is not normal.