Re: Design by Contract - out old struct member value

[Nick Treleaven via Digitalmars-d-learn]

On Wednesday, 6 August 2025 at 15:43:01 UTC, Brother Bill wrote:
How is this done in D?

I thought the following would work, but the compiler doesn't like 
`this.count` as a default argument:

```d
struct Counter {
   int count;

   void incrementBy(int increment, int preCount = this.count)
   in {
      assert(increment >= 0, "increment must be zero or greater");
   }
   out {
       assert(count == preCount + increment);
   }
   do {
      this.count += increment;
   }
}
```

And I expect you'd like to avoid adding a function parameter 
anyway.