From: Adam Shelly <adam.shelly@...>
Date: 2008-08-14T03:34:37+09:00
Subject: Re: How to do this?

On 8/13/08, Casimir <pikseli@nouuwelspamho.com> wrote:
> Dear sirs,
>
> I am planning a simple geometry generation library. XYZ points, primitive
> geometry such as triangles and guides that can generate more geometry.

I'll offer my opinions in reverse order:

> 2. How to achieve the '+' operation for symbols? For example symbol4 +
> somesymbol would join the geometry of the latter into the former. Or
> perhaps return a new symbol with combined geometry. How is that handled
> for adding number-objects?
>
Most (maybe even all) built-in + operators return a new object, so I'd
do the same for your Symbols.  Assuming a Symbol is just a collection
of primitives (lines and points), then it should probably be something
like:

class Symbol
  def initialize prims=[]
    @primitives = prims
  end
  def + other
     Symbol.new(@primitives +other.primitives )
  end
end

> So, suppose I would want to use the following syntax ...
>
> starcircle = Symbol.with_polygon(astar.polygon).along(Symbol.circle
(n_int, radius_int)))
>
> 1. How would one manage the generation of starcircle? Store the star
> ("astar") passed as argument in with_polygon in a Guide-instance and
> refer to it once "along"-method is called.

That could work, but is awkward.  What happens if you call #along
without #with first?  What if you call #with twice?

> Am I doing this wrong? Is this just artistic nonsens? Should it read, in
> a boring CS major style:
> starcircle = Symbol.generate_with_guide(astar, Symbol.circle)

How about a more ruby style:
tri =Symbol.triangle(side)
astar =  tri + tri.rotate(180)
circle = Symbol.circle(pts,radius)
starcircle = circle.map_points{|point|  astar.at(point).primitives }

where Symbol#at creates a new instance of itself centered on point, and
Symbol#map_points creates a new symbol based on the block results:

def map_points &block
 new_primitives = []
 @points.each{|pt| new_primitives<< block.call(pt)}
  Symbol.new(newpoints)
end



-Adam