Re: Exercise at end of Ch. 56 of "Programming in D"

[johntp via Digitalmars-d-learn]

On Monday, 15 August 2022 at 02:23:34 UTC, Ali Çehreli wrote:
Wow! Are people actually working on those? :)

Absolutely.  Thanks for the book.  I'm enjoying it.


At first, I couldn't even get the code to compile due to 
const-correctness issues with opCmp. :/ I used the following 
cast():

  foreach (i, point; points) {
      immutable comparison = (cast()point).opCmp(rhs.points[i]);
      // ...
  }


For some reason I didn't have this problem.


The bug was with trying to implement that unnatural "ignore the 
color" in the comparison logic but then toHash was taking 
advantage of existing array hashing code, which had no idea of 
the programmer's requirement:

I thought that was the problem, but wasn't sure.  I wasn't 
getting the same hash code for area1 and area2.

Your solution worked. I guess it is a little unnatural to ignore 
the color.  I tried overriding the toHash() of Point, but I don't 
know enough D to get it to work.  I wonder if that could be a 
solution.

Thanks so much for the reply.