Proper way to handle "alias this" deprecation for classes

[Salih Dincer]

On Sunday, 7 May 2023 at 21:04:05 UTC, Inkrementator wrote:
> Open question to everybody: What you're opinion on using opCast 
> for this? Since it's a type conversion, it seems fitting to me.

Can't converting without explicitly specifying in D is a big 
shortcoming in my opinion. There is such a thing as implicitly 
convertion though, but it's very confusing. I don't see that 
simplicity in C++ in the D codes!

```CPP
#include <iostream>
using namespace std;
struct Fraction {
     int num, den;

     Fraction(int n, int d) {
         num = n;
         den = d;
     }

     // Conversion operator: return float value of fraction
     operator float() const
     {
         return float(num) / float(den);
     }
};

int main()
{
     Fraction f(2, 5);
     float val = f;
     cout << val << '\n'; // 0.4
     return 0;
}
```

You should do the same in D like this:

```d
struct Fraction {
	int num, den;

	this(int n, int d)
	{
		num = n;
		den = d;
	}

	// Cast Expression : convert float value of fraction
	auto opCast(T : float)() const
	{
		return cast(float)(num) / cast(float)(den);
	}
}

import std.stdio;

int main()
{
	auto f = Fraction(2, 5);
	float val = cast(float)f;
	val.writeln; //0.4
	return 0;
}
```

SDB at 79