PolygonMesh triangulation... ?

Dan Rathbun

BUT.. that is not the point I was making. You do not need to mess with an index, in order to iterate the members of an Enumerable collection.

Restated and simplified, as this:

    for t in triplets
      t.each { |pt| pt.transform!(tra) }
    end

is faster and more readable (better practice) than:

    for i in 0...triplets.size
      triplets[i].each { |pt| pt.transform!(tra) }
    end

Why faster?

No calling the size method at the beginning.
No instantiation of a Range object via the ... operator
No need to call the [] method during each iteration.

There is no sense in using a index when you want the members of the enumerable collection.
Because, the for loop can directly serve up each enumerable member in turn, without the need to maintain an index variable on the Ruby side.

(Of course the C-side implementation using for over there does use an iterator, but the C-side does not need to expose the iterator to the Ruby side.)

The for construct is not a method it's built into Ruby. And it does not create a new scope during each iteration. I image that other built-in looping constructs ( while, until) can also be fast.

Dan Rathbun

@fredo6 said:

@anton_s said:

I think that each loop is slower than for loop. That's why I used for loop.

Not so sure in Ruby 2.x. See this interesting benchmark.

It is also said that the fastest is the while loop, when this is appropriate.

Well that is interesting. Seems they optimized while and each, but not for.
So now we have a quandary if we publish for older SketchUps, with older Ruby.

thomthom

IN Ruby 1.8 for loops used to be faster - at least in the tests I performed on my extensions. But Ruby 2.0 swapped that around.

In any case - you don't really know until you profile your specific case.