PartTree question

[dibyendumajumdar]

ray-optics/src/rayoptics/elem/parttree.py

Line 262 in 1d16241

for i, seg in enumerate(path):

In the above code, the variable i is defined in the for loop, but also modified inside the loop.
Trying to understand the intention here.

[mjhoptics]

This is code that I hope I never have to change again... The use cases it's attempting to handle include:

1. single lens
2. single mirror
3. cemented lenses (2 or more)
4. Mangin mirror (lens with mirror coat on rear surface, i.e. a buried reflector)
5. cemented Mangin mirror

The modification of i within the loop is intended and there are no side effects because every time thru the loop, the enumerate function returns a new value for i. I can't say that I'm proud of this code, but it works.

[dibyendumajumdar]

Okay thanks; it is a complex piece of logic there.