Re: Returning a reference to be manipulated

[Jacob Shtokolov via Digitalmars-d-learn]

On Thursday, 13 April 2023 at 07:05:10 UTC, Chris Katko wrote:
I'm trying to figure out how to return a reference to something 
that may not be a reference type.

```d
@safe:

struct Stats
{
    float[string] data;

    ref opIndex(string key) return
    {
        // The `require()` takes care of non-existing values, 
initializing them
        return data.require(key, 0);
    }
}

void main()
{
    import std.stdio;

    Stats foo;

    // 1. You can't "capture" a reference, only use it directly
    foo["tacos"] += 2;

    // 2. You can use an alternative function-calling form 
(sometimes replaced by the `with` operator)
    ((ref float val) => val += 2)(foo["burritos"]);

    // 3. As a last resort, use pointers or make struct wrappers 
around them
    auto x = &foo["quesadillas"];
    *x += 2;

    writeln(foo);
}
```