An example partial implementation along the lines of the comments of SLaks and others (feedback welcome):
Usage:
int x = 4;
iint pi = iint.PositiveInfinity;
iint ni = iint.NegativeInfinity;
Assert.IsTrue(x + pi == iint.PositiveInfinity);
Assert.IsTrue(pi + 1 == iint.PositiveInfinity);
Assert.IsTrue(pi + (-ni) == iint.PositiveInfinity);
Assert.IsTrue((int)((iint)5) == 5);
Implementation:
public struct iint
{
private readonly int _int;
public iint(int value)
{
if(value == int.MaxValue || value == int.MinValue)
throw new InvalidOperationException("min/max value reserved in iint");
_int = value;
}
public static explicit operator int(iint @this)
{
if(@this._int == int.MaxValue || @this._int == int.MinValue)
throw new InvalidOperationException("cannot implicit convert infinite iint to int");
return @this._int;
}
public static implicit operator iint(int other)
{
if(other == int.MaxValue || other == int.MinValue)
throw new InvalidOperationException("cannot implicit convert max-value into to iint");
return new iint(other);
}
public bool IsPositiveInfinity {get { return _int == int.MaxValue; } }
public bool IsNegativeInfinity { get { return _int == int.MinValue; } }
private iint(bool positive)
{
if (positive)
_int = int.MaxValue;
else
_int = int.MinValue;
}
public static readonly iint PositiveInfinity = new iint(true);
public static readonly iint NegativeInfinity = new iint(false);
public static bool operator ==(iint a, iint b)
{
return a._int == b._int;
}
public static bool operator !=(iint a, iint b)
{
return a._int != b._int;
}
public static iint operator +(iint a, iint b)
{
if (a.IsPositiveInfinity && b.IsNegativeInfinity)
throw new InvalidOperationException();
if (b.IsPositiveInfinity && a.IsNegativeInfinity)
throw new InvalidOperationException();
if (a.IsPositiveInfinity)
return PositiveInfinity;
if (a.IsNegativeInfinity)
return NegativeInfinity;
if (b.IsPositiveInfinity)
return PositiveInfinity;
if (b.IsNegativeInfinity)
return NegativeInfinity;
return a._int + b._int;
}
public static iint operator -(iint a, iint b)
{
if (a.IsPositiveInfinity && b.IsPositiveInfinity)
throw new InvalidOperationException();
if (a.IsNegativeInfinity && b.IsNegativeInfinity)
throw new InvalidOperationException();
if (a.IsPositiveInfinity)
return PositiveInfinity;
if (a.IsNegativeInfinity)
return NegativeInfinity;
if (b.IsPositiveInfinity)
return NegativeInfinity;
if (b.IsNegativeInfinity)
return PositiveInfinity;
return a._int - b._int;
}
public static iint operator -(iint a)
{
if (a.IsNegativeInfinity)
return PositiveInfinity;
if (a.IsPositiveInfinity)
return NegativeInfinity;
return -a;
}
/* etc... */
/* other operators here */
}