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Ron Beyer wrote:

works the same way that #define does in c++ to replace types.

using AgeInYears = System.Int32;
using AgeInDays = System.Int32;

...

AgeInYears yearAge = 10;
AgeInDays dayAge = 3650;

var myAge = yearAge + dayAge;    // OOPS!

namespace TestApp1
{
    using AgeInYears = System.Int32;
 
    class Program
    {
        static void Main(string[] args)
        {
            AgeInYears myAge = 10; // or whatever
            AgeInYears timeUntilOldAge = 10;
            AgeInYears oldAge = myAge + timeUntilOldAge;
        }
   }
}

Acceleration g = new Acceleration(9.88); // m/(s*s)
Mass m = new mass(25); // kg
Force f = m * g;

Pablo Aliskevicius wrote:

I remember reading an article (which I can't find) that used this to implement classes that allow you to do the following:

[<Measure>] type years

let myAge = 32<years>

Phil Martin wrote:

Units are lost at runtime

class AgeInYears : int
    {
    public static implicit operator AgeInYears(int i)
        {
        return (AgeInYears)i;
        }
    public static implicit operator int(AgeInYears a)
        {
        return (int)a;
        }
    }

OriginalGriff wrote:

Annoyingly, int is a sealed type in C#, or all you would have to do is provide the implicit cast operators:

OriginalGriff wrote:

And don't forget that an Age is not a constant value: it will vary as the application runs...

OriginalGriff wrote:

But...what is an age plus an age?

class AgeInYears
{
  public AgeInYears(DateTime birthdate)
  {
    _Birthdate = birthdate;
  }
  private DateTime _Birthdate;
  public int Years
  {
    get
    {
       return (DataTime.Now - _Birthdate).Days / 365; // yes, I know 365 isn't right; it's just an example, for gosh sakes
    }
  }
}

Gary Wheeler wrote:

The Ada programming language provided a semblance of semantic typing.

Rob Grainger wrote:

"If you don't fail at least 90 percent of the time, you're not aiming high enough."