import std.stdio;

struct Location {
    int r;
    int c;
}

struct Node {
    this(Location locaction, uint f) {
        this.location = location;
        this.f = f;
    }
    Location location;
    uint f;
}

void main() {
    Node n = Node(Location(1,2), 33);
    writeln("n = ", n);
}

---------------------------------------------------

produces:
n = Node(Location(0, 0), 33)
when I expected
n = Node(Location(1, 2), 33)


So structs are value objects (not reference like classes). So it is passed by value.  So a copy of 1 and 2 is made upon entering the constructor this.  But aren't these copies then placed into the Node structure n (for the lifetime of n). So that writeln should produce Location(1, 2), 33.

On Thursday, 9 January 2025 at 22:01:59 UTC, WhatMeWorry wrote:

this(Location locaction, uint f) {
    this.location = location;
    this.f = f;
}

You misspelled the parameter name 'locaction', so your assignment in the constructor is a no-op:

this.location = this.location

this.location = this.location

Thanks. I was starting to question my sanity.

On Thursday, 9 January 2025 at 22:01:59 UTC, WhatMeWorry wrote:

This is a simple typo (it shouldn't be 1 letter) but the code should be made smarter thanks to the capabilities of D. No more fear of writing like C and getting lost like C++. For example:

struct Location
{
  int x, y;

  auto opBinary(string op = "*")(uint m)
  {
    x *= m;
    y *= m;

    return this;
  }
}

import std.stdio;
void main()
{
  auto loca = Location(1, 2);
  auto node = Node(loca, 33);

  node.writefln!"n = %s";
}

struct Node
{
  uint multiplier;
  Location location;

  this(Location location, uint multiplier)
  {
    this.location = location * multiplier;
    this.multiplier = multiplier;
  }

}

SDB@79

I appreciate your example of the robustness of D, but if I was to make the same syntax mistake:

this(Location locaction, uint multiplier) // extraneous letter

it returns same error:

n = Node(33, Location(0, 0))

I guess there is no fix for stupidity on my part. :)

On Thursday, 9 January 2025 at 22:08:31 UTC, Dennis wrote:

this(Location locaction, uint f) {
    this.location = location;
    this.f = f;
}

this.location = this.location

If the compiler flags this as an warning -> he probably notice the problem
Lag of error/warn/hint for such case is not helping
Happy coding

On Thursday, 9 January 2025 at 22:08:31 UTC, Dennis wrote:

this(Location locaction, uint f) {
    this.location = location;
    this.f = f;
}

this.location = this.location

Which is why languages like Zig disallow such code ... unused variables must be identified as such.

On Thursday, 9 January 2025 at 23:44:52 UTC, WhatMeWorry wrote:

this.location = this.location

That error is so classic that eventually a well know linter detects it: https://pvs-studio.com/en/docs/warnings/v3196/

Sure that's not a D linter however.