Add Equals(T other, T maxError), obsolete Equals(T other) for Double quantities

Equality comparison is not safe with System.Double as internal representation.
Decimal quantities (Power, Information) still allow equality.
Add test on new Equals() method.

Author: angularsen

UnitsNet.Tests/GeneratedCode/LapseRateTestsBase.g.cs

@@ -15,7 +15,7 @@
 // </auto-generated>
 //------------------------------------------------------------------------------
 
-// Copyright (c) 2007 Andreas Gullberg Larsen (angularsen@gmail.com).
+// Copyright (c) 2007 Andreas Gullberg Larsen (andreas.larsen84@gmail.com).
 // https://github.com/angularsen/UnitsNet
 //
 // Permission is hereby granted, free of charge, to any person obtaining a copy

UnitsNet.Tests/GeneratedQuantityCodeTests.cs

@@ -0,0 +1,31 @@
+using Xunit;
+
+namespace UnitsNet.Tests
+{
+    /// <summary>
+    ///     Tests that cover generated code in quantity structs, such as <see cref="Length" /> and <see cref="Mass" />.
+    ///     The idea is to move tests that cover uniformly generated code here, because repeating the exact same test N times
+    ///     over don't make it safer.
+    /// </summary>
+    public class GeneratedQuantityCodeTests
+    {
+        /// <summary>
+        ///     Types with <see cref="double" /> as internal representation. This is the majority of units, such as
+        ///     <see cref="Length" />.
+        /// </summary>
+        public class QuantitiesWithDouble
+        {
+            [Fact]
+            public void LengthEquals_GivenMaxError_ReturnsTrueIfWithinError()
+            {
+                Length smallError = Length.FromMeters(1e-5);
+                Assert.True(Length.FromMeters(1).Equals(Length.FromMeters(1), Length.Zero), "Integer values have zero difference.");
+                Assert.True(Length.FromMeters(1).Equals(Length.FromMeters(1), smallError), "Using a max difference value should not change that fact.");
+
+                Assert.False(Length.FromMeters(1 + 0.39).Equals(Length.FromMeters(1.39), Length.Zero),
+                    "Example of floating precision arithmetic that produces slightly different results.");
+                Assert.True(Length.FromMeters(1 + 0.39).Equals(Length.FromMeters(1.39), smallError), "But the difference is very small");
+            }
+        }
+    }
+}

UnitsNet/GeneratedCode/Extensions/Number/NumberToLapseRateExtensions.g.cs

@@ -15,7 +15,7 @@
 // </auto-generated>
 //------------------------------------------------------------------------------
 
-// Copyright (c) 2007 Andreas Gullberg Larsen (angularsen@gmail.com).
+// Copyright (c) 2007 Andreas Gullberg Larsen (andreas.larsen84@gmail.com).
 // https://github.com/angularsen/UnitsNet
 // 
 // Permission is hereby granted, free of charge, to any person obtaining a copy

UnitsNet/GeneratedCode/Quantities/Acceleration.g.cs

@@ -1060,19 +1060,22 @@ int CompareTo(Acceleration other)
             return left._meterPerSecondSquared > right._meterPerSecondSquared;
         }
 
+        [Obsolete("It is not safe to compare equality due to using System.Double as the internal representation. It is very easy to get slightly different values due to floating point operations. Instead use Equals(other, maxError) to provide the max allowed error.")]
         public static bool operator ==(Acceleration left, Acceleration right)
         {
             // ReSharper disable once CompareOfFloatsByEqualityOperator
             return left._meterPerSecondSquared == right._meterPerSecondSquared;
         }
 
+        [Obsolete("It is not safe to compare equality due to using System.Double as the internal representation. It is very easy to get slightly different values due to floating point operations. Instead use Equals(other, maxError) to provide the max allowed error.")]
         public static bool operator !=(Acceleration left, Acceleration right)
         {
             // ReSharper disable once CompareOfFloatsByEqualityOperator
             return left._meterPerSecondSquared != right._meterPerSecondSquared;
         }
 #endif
 
+        [Obsolete("It is not safe to compare equality due to using System.Double as the internal representation. It is very easy to get slightly different values due to floating point operations. Instead use Equals(other, maxError) to provide the max allowed error.")]
         public override bool Equals(object obj)
         {
             if (obj == null || GetType() != obj.GetType())
@@ -1083,6 +1086,19 @@ public override bool Equals(object obj)
             return _meterPerSecondSquared.Equals(((Acceleration) obj)._meterPerSecondSquared);
         }
 
+        /// <summary>
+        ///     Compare equality to another Acceleration by specifying a max allowed difference.
+        ///     Note that it is advised against specifying zero difference, due to the nature
+        ///     of floating point operations and using System.Double internally.
+        /// </summary>
+        /// <param name="other">Other quantity to compare to.</param>
+        /// <param name="maxError">Max error allowed.</param>
+        /// <returns>True if the difference between the two values is not greater than the specified max.</returns>
+        public bool Equals(Acceleration other, Acceleration maxError)
+        {
+            return Math.Abs(_meterPerSecondSquared - other._meterPerSecondSquared) <= maxError._meterPerSecondSquared;
+        }
+
         public override int GetHashCode()
         {
             return _meterPerSecondSquared.GetHashCode();

UnitsNet/GeneratedCode/Quantities/AmountOfSubstance.g.cs

@@ -1830,19 +1830,22 @@ int CompareTo(AmountOfSubstance other)
             return left._moles > right._moles;
         }
 
+        [Obsolete("It is not safe to compare equality due to using System.Double as the internal representation. It is very easy to get slightly different values due to floating point operations. Instead use Equals(other, maxError) to provide the max allowed error.")]
         public static bool operator ==(AmountOfSubstance left, AmountOfSubstance right)
         {
             // ReSharper disable once CompareOfFloatsByEqualityOperator
             return left._moles == right._moles;
         }
 
+        [Obsolete("It is not safe to compare equality due to using System.Double as the internal representation. It is very easy to get slightly different values due to floating point operations. Instead use Equals(other, maxError) to provide the max allowed error.")]
         public static bool operator !=(AmountOfSubstance left, AmountOfSubstance right)
         {
             // ReSharper disable once CompareOfFloatsByEqualityOperator
             return left._moles != right._moles;
         }
 #endif
 
+        [Obsolete("It is not safe to compare equality due to using System.Double as the internal representation. It is very easy to get slightly different values due to floating point operations. Instead use Equals(other, maxError) to provide the max allowed error.")]
         public override bool Equals(object obj)
         {
             if (obj == null || GetType() != obj.GetType())
@@ -1853,6 +1856,19 @@ public override bool Equals(object obj)
             return _moles.Equals(((AmountOfSubstance) obj)._moles);
         }
 
+        /// <summary>
+        ///     Compare equality to another AmountOfSubstance by specifying a max allowed difference.
+        ///     Note that it is advised against specifying zero difference, due to the nature
+        ///     of floating point operations and using System.Double internally.
+        /// </summary>
+        /// <param name="other">Other quantity to compare to.</param>
+        /// <param name="maxError">Max error allowed.</param>
+        /// <returns>True if the difference between the two values is not greater than the specified max.</returns>
+        public bool Equals(AmountOfSubstance other, AmountOfSubstance maxError)
+        {
+            return Math.Abs(_moles - other._moles) <= maxError._moles;
+        }
+
         public override int GetHashCode()
         {
             return _moles.GetHashCode();

UnitsNet/GeneratedCode/Quantities/AmplitudeRatio.g.cs

@@ -738,19 +738,22 @@ int CompareTo(AmplitudeRatio other)
             return left._decibelVolts > right._decibelVolts;
         }
 
+        [Obsolete("It is not safe to compare equality due to using System.Double as the internal representation. It is very easy to get slightly different values due to floating point operations. Instead use Equals(other, maxError) to provide the max allowed error.")]
         public static bool operator ==(AmplitudeRatio left, AmplitudeRatio right)
         {
             // ReSharper disable once CompareOfFloatsByEqualityOperator
             return left._decibelVolts == right._decibelVolts;
         }
 
+        [Obsolete("It is not safe to compare equality due to using System.Double as the internal representation. It is very easy to get slightly different values due to floating point operations. Instead use Equals(other, maxError) to provide the max allowed error.")]
         public static bool operator !=(AmplitudeRatio left, AmplitudeRatio right)
         {
             // ReSharper disable once CompareOfFloatsByEqualityOperator
             return left._decibelVolts != right._decibelVolts;
         }
 #endif
 
+        [Obsolete("It is not safe to compare equality due to using System.Double as the internal representation. It is very easy to get slightly different values due to floating point operations. Instead use Equals(other, maxError) to provide the max allowed error.")]
         public override bool Equals(object obj)
         {
             if (obj == null || GetType() != obj.GetType())
@@ -761,6 +764,19 @@ public override bool Equals(object obj)
             return _decibelVolts.Equals(((AmplitudeRatio) obj)._decibelVolts);
         }
 
+        /// <summary>
+        ///     Compare equality to another AmplitudeRatio by specifying a max allowed difference.
+        ///     Note that it is advised against specifying zero difference, due to the nature
+        ///     of floating point operations and using System.Double internally.
+        /// </summary>
+        /// <param name="other">Other quantity to compare to.</param>
+        /// <param name="maxError">Max error allowed.</param>
+        /// <returns>True if the difference between the two values is not greater than the specified max.</returns>
+        public bool Equals(AmplitudeRatio other, AmplitudeRatio maxError)
+        {
+            return Math.Abs(_decibelVolts - other._decibelVolts) <= maxError._decibelVolts;
+        }
+
         public override int GetHashCode()
         {
             return _decibelVolts.GetHashCode();

UnitsNet/GeneratedCode/Quantities/Angle.g.cs

@@ -1720,19 +1720,22 @@ int CompareTo(Angle other)
             return left._degrees > right._degrees;
         }
 
+        [Obsolete("It is not safe to compare equality due to using System.Double as the internal representation. It is very easy to get slightly different values due to floating point operations. Instead use Equals(other, maxError) to provide the max allowed error.")]
         public static bool operator ==(Angle left, Angle right)
         {
             // ReSharper disable once CompareOfFloatsByEqualityOperator
             return left._degrees == right._degrees;
         }
 
+        [Obsolete("It is not safe to compare equality due to using System.Double as the internal representation. It is very easy to get slightly different values due to floating point operations. Instead use Equals(other, maxError) to provide the max allowed error.")]
         public static bool operator !=(Angle left, Angle right)
         {
             // ReSharper disable once CompareOfFloatsByEqualityOperator
             return left._degrees != right._degrees;
         }
 #endif
 
+        [Obsolete("It is not safe to compare equality due to using System.Double as the internal representation. It is very easy to get slightly different values due to floating point operations. Instead use Equals(other, maxError) to provide the max allowed error.")]
         public override bool Equals(object obj)
         {
             if (obj == null || GetType() != obj.GetType())
@@ -1743,6 +1746,19 @@ public override bool Equals(object obj)
             return _degrees.Equals(((Angle) obj)._degrees);
         }
 
+        /// <summary>
+        ///     Compare equality to another Angle by specifying a max allowed difference.
+        ///     Note that it is advised against specifying zero difference, due to the nature
+        ///     of floating point operations and using System.Double internally.
+        /// </summary>
+        /// <param name="other">Other quantity to compare to.</param>
+        /// <param name="maxError">Max error allowed.</param>
+        /// <returns>True if the difference between the two values is not greater than the specified max.</returns>
+        public bool Equals(Angle other, Angle maxError)
+        {
+            return Math.Abs(_degrees - other._degrees) <= maxError._degrees;
+        }
+
         public override int GetHashCode()
         {
             return _degrees.GetHashCode();

UnitsNet/GeneratedCode/Quantities/ApparentPower.g.cs

@@ -620,19 +620,22 @@ int CompareTo(ApparentPower other)
             return left._voltamperes > right._voltamperes;
         }
 
+        [Obsolete("It is not safe to compare equality due to using System.Double as the internal representation. It is very easy to get slightly different values due to floating point operations. Instead use Equals(other, maxError) to provide the max allowed error.")]
         public static bool operator ==(ApparentPower left, ApparentPower right)
         {
             // ReSharper disable once CompareOfFloatsByEqualityOperator
             return left._voltamperes == right._voltamperes;
         }
 
+        [Obsolete("It is not safe to compare equality due to using System.Double as the internal representation. It is very easy to get slightly different values due to floating point operations. Instead use Equals(other, maxError) to provide the max allowed error.")]
         public static bool operator !=(ApparentPower left, ApparentPower right)
         {
             // ReSharper disable once CompareOfFloatsByEqualityOperator
             return left._voltamperes != right._voltamperes;
         }
 #endif
 
+        [Obsolete("It is not safe to compare equality due to using System.Double as the internal representation. It is very easy to get slightly different values due to floating point operations. Instead use Equals(other, maxError) to provide the max allowed error.")]
         public override bool Equals(object obj)
         {
             if (obj == null || GetType() != obj.GetType())
@@ -643,6 +646,19 @@ public override bool Equals(object obj)
             return _voltamperes.Equals(((ApparentPower) obj)._voltamperes);
         }
 
+        /// <summary>
+        ///     Compare equality to another ApparentPower by specifying a max allowed difference.
+        ///     Note that it is advised against specifying zero difference, due to the nature
+        ///     of floating point operations and using System.Double internally.
+        /// </summary>
+        /// <param name="other">Other quantity to compare to.</param>
+        /// <param name="maxError">Max error allowed.</param>
+        /// <returns>True if the difference between the two values is not greater than the specified max.</returns>
+        public bool Equals(ApparentPower other, ApparentPower maxError)
+        {
+            return Math.Abs(_voltamperes - other._voltamperes) <= maxError._voltamperes;
+        }
+
         public override int GetHashCode()
         {
             return _voltamperes.GetHashCode();

UnitsNet/GeneratedCode/Quantities/Area.g.cs

@@ -1610,19 +1610,22 @@ int CompareTo(Area other)
             return left._squareMeters > right._squareMeters;
         }
 
+        [Obsolete("It is not safe to compare equality due to using System.Double as the internal representation. It is very easy to get slightly different values due to floating point operations. Instead use Equals(other, maxError) to provide the max allowed error.")]
         public static bool operator ==(Area left, Area right)
         {
             // ReSharper disable once CompareOfFloatsByEqualityOperator
             return left._squareMeters == right._squareMeters;
         }
 
+        [Obsolete("It is not safe to compare equality due to using System.Double as the internal representation. It is very easy to get slightly different values due to floating point operations. Instead use Equals(other, maxError) to provide the max allowed error.")]
         public static bool operator !=(Area left, Area right)
         {
             // ReSharper disable once CompareOfFloatsByEqualityOperator
             return left._squareMeters != right._squareMeters;
         }
 #endif
 
+        [Obsolete("It is not safe to compare equality due to using System.Double as the internal representation. It is very easy to get slightly different values due to floating point operations. Instead use Equals(other, maxError) to provide the max allowed error.")]
         public override bool Equals(object obj)
         {
             if (obj == null || GetType() != obj.GetType())
@@ -1633,6 +1636,19 @@ public override bool Equals(object obj)
             return _squareMeters.Equals(((Area) obj)._squareMeters);
         }
 
+        /// <summary>
+        ///     Compare equality to another Area by specifying a max allowed difference.
+        ///     Note that it is advised against specifying zero difference, due to the nature
+        ///     of floating point operations and using System.Double internally.
+        /// </summary>
+        /// <param name="other">Other quantity to compare to.</param>
+        /// <param name="maxError">Max error allowed.</param>
+        /// <returns>True if the difference between the two values is not greater than the specified max.</returns>
+        public bool Equals(Area other, Area maxError)
+        {
+            return Math.Abs(_squareMeters - other._squareMeters) <= maxError._squareMeters;
+        }
+
         public override int GetHashCode()
         {
             return _squareMeters.GetHashCode();

UnitsNet/GeneratedCode/Quantities/AreaMomentOfInertia.g.cs

@@ -950,19 +950,22 @@ int CompareTo(AreaMomentOfInertia other)
             return left._metersToTheFourth > right._metersToTheFourth;
         }
 
+        [Obsolete("It is not safe to compare equality due to using System.Double as the internal representation. It is very easy to get slightly different values due to floating point operations. Instead use Equals(other, maxError) to provide the max allowed error.")]
         public static bool operator ==(AreaMomentOfInertia left, AreaMomentOfInertia right)
         {
             // ReSharper disable once CompareOfFloatsByEqualityOperator
             return left._metersToTheFourth == right._metersToTheFourth;
         }
 
+        [Obsolete("It is not safe to compare equality due to using System.Double as the internal representation. It is very easy to get slightly different values due to floating point operations. Instead use Equals(other, maxError) to provide the max allowed error.")]
         public static bool operator !=(AreaMomentOfInertia left, AreaMomentOfInertia right)
         {
             // ReSharper disable once CompareOfFloatsByEqualityOperator
             return left._metersToTheFourth != right._metersToTheFourth;
         }
 #endif
 
+        [Obsolete("It is not safe to compare equality due to using System.Double as the internal representation. It is very easy to get slightly different values due to floating point operations. Instead use Equals(other, maxError) to provide the max allowed error.")]
         public override bool Equals(object obj)
         {
             if (obj == null || GetType() != obj.GetType())
@@ -973,6 +976,19 @@ public override bool Equals(object obj)
             return _metersToTheFourth.Equals(((AreaMomentOfInertia) obj)._metersToTheFourth);
         }
 
+        /// <summary>
+        ///     Compare equality to another AreaMomentOfInertia by specifying a max allowed difference.
+        ///     Note that it is advised against specifying zero difference, due to the nature
+        ///     of floating point operations and using System.Double internally.
+        /// </summary>
+        /// <param name="other">Other quantity to compare to.</param>
+        /// <param name="maxError">Max error allowed.</param>
+        /// <returns>True if the difference between the two values is not greater than the specified max.</returns>
+        public bool Equals(AreaMomentOfInertia other, AreaMomentOfInertia maxError)
+        {
+            return Math.Abs(_metersToTheFourth - other._metersToTheFourth) <= maxError._metersToTheFourth;
+        }
+
         public override int GetHashCode()
         {
             return _metersToTheFourth.GetHashCode();