Introduction of IUnknown<TSelf>

.editorconfig

@@ -103,6 +103,7 @@ dotnet_diagnostic.S2328.severity = none # GetHashCode() should not reference mut
 dotnet_diagnostic.S2178.severity = none # Short-circuit logic should be used in boolean contexts - '&' is used instead of && to accommodate expressions with nullable booleans too.
 dotnet_diagnostic.S3376.severity = none # EventArgs, and Exception type names should end with the type being extended
 dotnet_diagnostic.S3376.severity = none # Attribute, EventArgs, and Exception type names should end with the type being extended
+dotnet_diagnostic.S3925.severity = none # "ISerializable" should be implemented correctly
 dotnet_diagnostic.S4136.severity = none # Method overloads should be grouped together
 
 dotnet_diagnostic.S1133.severity = suggestion # Deprecated code should be removed
@@ -130,7 +131,6 @@ dotnet_diagnostic.S3215.severity = warning # Interface instances should not be c
 dotnet_diagnostic.S3218.severity = warning # Inner class members should not shadow outer class "static" or type members
 dotnet_diagnostic.S3257.severity = warning # Declarations and initializations should be as concise as possible
 dotnet_diagnostic.S3776.severity = warning # Cognitive Complexity of methods should not be too high
-dotnet_diagnostic.S3925.severity = warning # "ISerializable" should be implemented correctly
 dotnet_diagnostic.S6354.severity = warning # Use a testable (date) time provider instead
 
 dotnet_diagnostic.VSSpell001.severity = silent # Correct spelling

specs/Qowaiv.Specs/Financial/Amount_specs.cs

@@ -1,5 +1,14 @@
 namespace Financial.Amount_specs;
 
+public class Has_constant
+{
+    [Test]
+    public void MinValue_equal_to_decimal_MinValue() => Amount.MinValue.Should().Be(decimal.MinValue.Amount());
+
+    [Test]
+    public void MaxValue_equal_to_decimal_MaxValue() => Amount.MaxValue.Should().Be(decimal.MaxValue.Amount());
+}
+
 public class Min_and_max
 {
     [TestCase(17, 17)]

src/Qowaiv/Chemistry/CasRegistryNumber.cs

@@ -21,7 +21,7 @@ namespace Qowaiv.Chemistry;
 public readonly partial struct CasRegistryNumber : IXmlSerializable, IFormattable, IEquatable<CasRegistryNumber>, IComparable, IComparable<CasRegistryNumber>
 {
     /// <summary>Represents an unknown (but set) CAS Registry Number.</summary>
-    public static readonly CasRegistryNumber Unknown = new(long.MaxValue);
+    public static CasRegistryNumber Unknown => new(long.MaxValue);
 
     /// <summary>Gets the number of characters of CAS Registry Number.</summary>
     public int Length => IsEmptyOrUnknown() ? 0 : (int)Math.Ceiling(Math.Log10(m_Value));

src/Qowaiv/Contracts/IUnknown.cs

@@ -0,0 +1,18 @@
+namespace Qowaiv;
+
+/// <summary>
+/// Defines that the default of an SVO represents the empty/not set state.
+/// </summary>
+/// <typeparam name="TSelf">
+/// The type of the SVO.
+/// </typeparam>
+public interface IUnknown<TSelf> : IEmpty<TSelf> where TSelf : struct, IEmpty<TSelf>
+{
+#if NET8_0_OR_GREATER
+    /// <summary>Represents an unknown (but set) <typeparamref name="TSelf"/>.</summary>
+    static abstract TSelf Unknown { get; }
+#endif
+
+    /// <summary>False if <typeparamref name="TSelf"/> is empty or unknown, otherwise true.</summary>
+    bool IsKnown { get; }
+}

src/Qowaiv/Customization/Svo.cs

@@ -1,4 +1,4 @@
-#pragma warning disable S1210
+#pragma warning disable S1210
 // "Equals" and the comparison operators should be overridden when implementing "IComparable"
 // See README.md => Sortable
 using Qowaiv.Conversion.Customization;
@@ -17,7 +17,7 @@ namespace Qowaiv.Customization;
 #if NET6_0_OR_GREATER
 [System.Text.Json.Serialization.JsonConverter(typeof(Json.Customization.GenericSvoJsonConverter))]
 #endif
-public readonly struct Svo<TSvoBehavior> : IXmlSerializable, IFormattable, IEquatable<Svo<TSvoBehavior>>, IComparable, IComparable<Svo<TSvoBehavior>>, IEmpty<Svo<TSvoBehavior>>
+public readonly struct Svo<TSvoBehavior> : IXmlSerializable, IFormattable, IEquatable<Svo<TSvoBehavior>>, IComparable, IComparable<Svo<TSvoBehavior>>, IUnknown<Svo<TSvoBehavior>>
 #if NET8_0_OR_GREATER
 , IEqualityOperators<Svo<TSvoBehavior>, Svo<TSvoBehavior>, bool>
 , IParsable<Svo<TSvoBehavior>>
@@ -34,7 +34,7 @@ namespace Qowaiv.Customization;
     public static Svo<TSvoBehavior> Empty => default;
 
     /// <summary>Represents an unknown (but set) Single Value Object.</summary>
-    public static readonly Svo<TSvoBehavior> Unknown = new(SvoBehavior.unknown);
+    public static Svo<TSvoBehavior> Unknown => new(SvoBehavior.unknown);
 
     /// <summary>Initializes a new instance of the <see cref="Svo{TSvoBehavior}"/> struct.</summary>
     private Svo(string? value) => m_Value = value;

src/Qowaiv/EmailAddress.cs

@@ -23,7 +23,7 @@ namespace Qowaiv;
     public const int MaxLength = 254;
 
     /// <summary>Represents an unknown (but set) email address.</summary>
-    public static readonly EmailAddress Unknown = new("?");
+    public static EmailAddress Unknown => new("?");
 
     /// <summary>Gets the number of characters of email address.</summary>
     public int Length => m_Value is { Length: > 1 } ? m_Value.Length : 0;

src/Qowaiv/Financial/BusinessIdentifierCode.cs

@@ -43,7 +43,7 @@ namespace Qowaiv.Financial;
 #endif
 
     /// <summary>Represents an unknown (but set) BIC.</summary>
-    public static readonly BusinessIdentifierCode Unknown = new("ZZZZZZZZZZZ");
+    public static BusinessIdentifierCode Unknown => new("ZZZZZZZZZZZ");
 
     /// <summary>Gets the number of characters of BIC.</summary>
     public int Length => IsUnknown() ? 0 : m_Value?.Length ?? 0;

src/Qowaiv/Financial/Currency.cs

@@ -29,7 +29,7 @@ namespace Qowaiv.Financial;
 public readonly partial struct Currency : IXmlSerializable, IFormattable, IFormatProvider, IEquatable<Currency>, IComparable, IComparable<Currency>
 {
     /// <summary>Represents an unknown (but set) currency.</summary>
-    public static readonly Currency Unknown = new("ZZZ");
+    public static Currency Unknown => new("ZZZ");
 
     /// <summary>Gets a currency based on the current thread.</summary>
     public static Currency Current => Thread.CurrentThread.GetValue<Currency>();

src/Qowaiv/Financial/InternationalBankAccountNumber.cs

@@ -27,7 +27,7 @@ namespace Qowaiv.Financial;
 public readonly partial struct InternationalBankAccountNumber : IXmlSerializable, IFormattable, IEquatable<InternationalBankAccountNumber>, IComparable, IComparable<InternationalBankAccountNumber>
 {
     /// <summary>Represents an unknown (but set) IBAN.</summary>
-    public static readonly InternationalBankAccountNumber Unknown = new("ZZ");
+    public static InternationalBankAccountNumber Unknown => new("ZZ");
 
     /// <summary>Gets the number of characters of IBAN.</summary>
     public int Length => m_Value is { Length: > 2 } ? m_Value.Length : 0;

src/Qowaiv/Generated/Chemistry/CasRegistryNumber.generated.cs

@@ -18,18 +18,6 @@ public partial struct CasRegistryNumber
     /// <summary>The inner value of the CAS Registry Number.</summary>
     [DebuggerBrowsable(DebuggerBrowsableState.Never)]
     private readonly long m_Value;
-
-    /// <summary>False if the CAS Registry Number is empty or unknown, otherwise true.</summary>
-    [DebuggerBrowsable(DebuggerBrowsableState.Never)]
-    public bool IsKnown => m_Value != default && m_Value != Unknown.m_Value;
-
-    /// <summary>Returns true if the CAS Registry Number is unknown, otherwise false.</summary>
-    [Pure]
-    public bool IsUnknown() => m_Value == Unknown.m_Value;
-
-    /// <summary>Returns true if the CAS Registry Number is empty or unknown, otherwise false.</summary>
-    [Pure]
-    public bool IsEmptyOrUnknown() => IsEmpty() || IsUnknown();
 }
 
 public partial struct CasRegistryNumber : IEmpty<CasRegistryNumber>
@@ -46,6 +34,21 @@ public partial struct CasRegistryNumber : IEmpty<CasRegistryNumber>
     public bool IsEmpty() => !HasValue;
 }
 
+public partial struct CasRegistryNumber : IUnknown<CasRegistryNumber>
+{
+    /// <summary>False if the CAS Registry Number is empty or unknown, otherwise true.</summary>
+    [DebuggerBrowsable(DebuggerBrowsableState.Never)]
+    public bool IsKnown => m_Value != default && m_Value != Unknown.m_Value;
+
+    /// <summary>Returns true if the CAS Registry Number is unknown, otherwise false.</summary>
+    [Pure]
+    public bool IsUnknown() => m_Value == Unknown.m_Value;
+
+    /// <summary>Returns true if the CAS Registry Number is empty or unknown, otherwise false.</summary>
+    [Pure]
+    public bool IsEmptyOrUnknown() => IsEmpty() || IsUnknown();
+}
+
 public partial struct CasRegistryNumber : IEquatable<CasRegistryNumber>
 #if NET8_0_OR_GREATER
     , IEqualityOperators<CasRegistryNumber, CasRegistryNumber, bool>

src/Qowaiv/Generated/EmailAddress.generated.cs

@@ -18,18 +18,6 @@ public partial struct EmailAddress
     /// <summary>The inner value of the email address.</summary>
     [DebuggerBrowsable(DebuggerBrowsableState.Never)]
     private readonly string? m_Value;
-
-    /// <summary>False if the email address is empty or unknown, otherwise true.</summary>
-    [DebuggerBrowsable(DebuggerBrowsableState.Never)]
-    public bool IsKnown => m_Value != default && m_Value != Unknown.m_Value;
-
-    /// <summary>Returns true if the email address is unknown, otherwise false.</summary>
-    [Pure]
-    public bool IsUnknown() => m_Value == Unknown.m_Value;
-
-    /// <summary>Returns true if the email address is empty or unknown, otherwise false.</summary>
-    [Pure]
-    public bool IsEmptyOrUnknown() => IsEmpty() || IsUnknown();
 }
 
 public partial struct EmailAddress : IEmpty<EmailAddress>
@@ -46,6 +34,21 @@ public partial struct EmailAddress : IEmpty<EmailAddress>
     public bool IsEmpty() => !HasValue;
 }
 
+public partial struct EmailAddress : IUnknown<EmailAddress>
+{
+    /// <summary>False if the email address is empty or unknown, otherwise true.</summary>
+    [DebuggerBrowsable(DebuggerBrowsableState.Never)]
+    public bool IsKnown => m_Value != default && m_Value != Unknown.m_Value;
+
+    /// <summary>Returns true if the email address is unknown, otherwise false.</summary>
+    [Pure]
+    public bool IsUnknown() => m_Value == Unknown.m_Value;
+
+    /// <summary>Returns true if the email address is empty or unknown, otherwise false.</summary>
+    [Pure]
+    public bool IsEmptyOrUnknown() => IsEmpty() || IsUnknown();
+}
+
 public partial struct EmailAddress : IEquatable<EmailAddress>
 #if NET8_0_OR_GREATER
     , IEqualityOperators<EmailAddress, EmailAddress, bool>

src/Qowaiv/Generated/Financial/BusinessIdentifierCode.generated.cs

@@ -18,18 +18,6 @@ public partial struct BusinessIdentifierCode
     /// <summary>The inner value of the BIC.</summary>
     [DebuggerBrowsable(DebuggerBrowsableState.Never)]
     private readonly string? m_Value;
-
-    /// <summary>False if the BIC is empty or unknown, otherwise true.</summary>
-    [DebuggerBrowsable(DebuggerBrowsableState.Never)]
-    public bool IsKnown => m_Value != default && m_Value != Unknown.m_Value;
-
-    /// <summary>Returns true if the BIC is unknown, otherwise false.</summary>
-    [Pure]
-    public bool IsUnknown() => m_Value == Unknown.m_Value;
-
-    /// <summary>Returns true if the BIC is empty or unknown, otherwise false.</summary>
-    [Pure]
-    public bool IsEmptyOrUnknown() => IsEmpty() || IsUnknown();
 }
 
 public partial struct BusinessIdentifierCode : IEmpty<BusinessIdentifierCode>
@@ -46,6 +34,21 @@ public partial struct BusinessIdentifierCode : IEmpty<BusinessIdentifierCode>
     public bool IsEmpty() => !HasValue;
 }
 
+public partial struct BusinessIdentifierCode : IUnknown<BusinessIdentifierCode>
+{
+    /// <summary>False if the BIC is empty or unknown, otherwise true.</summary>
+    [DebuggerBrowsable(DebuggerBrowsableState.Never)]
+    public bool IsKnown => m_Value != default && m_Value != Unknown.m_Value;
+
+    /// <summary>Returns true if the BIC is unknown, otherwise false.</summary>
+    [Pure]
+    public bool IsUnknown() => m_Value == Unknown.m_Value;
+
+    /// <summary>Returns true if the BIC is empty or unknown, otherwise false.</summary>
+    [Pure]
+    public bool IsEmptyOrUnknown() => IsEmpty() || IsUnknown();
+}
+
 public partial struct BusinessIdentifierCode : IEquatable<BusinessIdentifierCode>
 #if NET8_0_OR_GREATER
     , IEqualityOperators<BusinessIdentifierCode, BusinessIdentifierCode, bool>

src/Qowaiv/Generated/Financial/Currency.generated.cs

@@ -18,18 +18,6 @@ public partial struct Currency
     /// <summary>The inner value of the currency.</summary>
     [DebuggerBrowsable(DebuggerBrowsableState.Never)]
     private readonly string? m_Value;
-
-    /// <summary>False if the currency is empty or unknown, otherwise true.</summary>
-    [DebuggerBrowsable(DebuggerBrowsableState.Never)]
-    public bool IsKnown => m_Value != default && m_Value != Unknown.m_Value;
-
-    /// <summary>Returns true if the currency is unknown, otherwise false.</summary>
-    [Pure]
-    public bool IsUnknown() => m_Value == Unknown.m_Value;
-
-    /// <summary>Returns true if the currency is empty or unknown, otherwise false.</summary>
-    [Pure]
-    public bool IsEmptyOrUnknown() => IsEmpty() || IsUnknown();
 }
 
 public partial struct Currency : IEmpty<Currency>
@@ -46,6 +34,21 @@ public partial struct Currency : IEmpty<Currency>
     public bool IsEmpty() => !HasValue;
 }
 
+public partial struct Currency : IUnknown<Currency>
+{
+    /// <summary>False if the currency is empty or unknown, otherwise true.</summary>
+    [DebuggerBrowsable(DebuggerBrowsableState.Never)]
+    public bool IsKnown => m_Value != default && m_Value != Unknown.m_Value;
+
+    /// <summary>Returns true if the currency is unknown, otherwise false.</summary>
+    [Pure]
+    public bool IsUnknown() => m_Value == Unknown.m_Value;
+
+    /// <summary>Returns true if the currency is empty or unknown, otherwise false.</summary>
+    [Pure]
+    public bool IsEmptyOrUnknown() => IsEmpty() || IsUnknown();
+}
+
 public partial struct Currency : IEquatable<Currency>
 #if NET8_0_OR_GREATER
     , IEqualityOperators<Currency, Currency, bool>

src/Qowaiv/Generated/Financial/InternationalBankAccountNumber.generated.cs

@@ -18,18 +18,6 @@ public partial struct InternationalBankAccountNumber
     /// <summary>The inner value of the IBAN.</summary>
     [DebuggerBrowsable(DebuggerBrowsableState.Never)]
     private readonly string? m_Value;
-
-    /// <summary>False if the IBAN is empty or unknown, otherwise true.</summary>
-    [DebuggerBrowsable(DebuggerBrowsableState.Never)]
-    public bool IsKnown => m_Value != default && m_Value != Unknown.m_Value;
-
-    /// <summary>Returns true if the IBAN is unknown, otherwise false.</summary>
-    [Pure]
-    public bool IsUnknown() => m_Value == Unknown.m_Value;
-
-    /// <summary>Returns true if the IBAN is empty or unknown, otherwise false.</summary>
-    [Pure]
-    public bool IsEmptyOrUnknown() => IsEmpty() || IsUnknown();
 }
 
 public partial struct InternationalBankAccountNumber : IEmpty<InternationalBankAccountNumber>
@@ -46,6 +34,21 @@ public partial struct InternationalBankAccountNumber : IEmpty<InternationalBankA
     public bool IsEmpty() => !HasValue;
 }
 
+public partial struct InternationalBankAccountNumber : IUnknown<InternationalBankAccountNumber>
+{
+    /// <summary>False if the IBAN is empty or unknown, otherwise true.</summary>
+    [DebuggerBrowsable(DebuggerBrowsableState.Never)]
+    public bool IsKnown => m_Value != default && m_Value != Unknown.m_Value;
+
+    /// <summary>Returns true if the IBAN is unknown, otherwise false.</summary>
+    [Pure]
+    public bool IsUnknown() => m_Value == Unknown.m_Value;
+
+    /// <summary>Returns true if the IBAN is empty or unknown, otherwise false.</summary>
+    [Pure]
+    public bool IsEmptyOrUnknown() => IsEmpty() || IsUnknown();
+}
+
 public partial struct InternationalBankAccountNumber : IEquatable<InternationalBankAccountNumber>
 #if NET8_0_OR_GREATER
     , IEqualityOperators<InternationalBankAccountNumber, InternationalBankAccountNumber, bool>

src/Qowaiv/Generated/Globalization/Country.generated.cs

@@ -18,18 +18,6 @@ public partial struct Country
     /// <summary>The inner value of the country.</summary>
     [DebuggerBrowsable(DebuggerBrowsableState.Never)]
     private readonly string? m_Value;
-
-    /// <summary>False if the country is empty or unknown, otherwise true.</summary>
-    [DebuggerBrowsable(DebuggerBrowsableState.Never)]
-    public bool IsKnown => m_Value != default && m_Value != Unknown.m_Value;
-
-    /// <summary>Returns true if the country is unknown, otherwise false.</summary>
-    [Pure]
-    public bool IsUnknown() => m_Value == Unknown.m_Value;
-
-    /// <summary>Returns true if the country is empty or unknown, otherwise false.</summary>
-    [Pure]
-    public bool IsEmptyOrUnknown() => IsEmpty() || IsUnknown();
 }
 
 public partial struct Country : IEmpty<Country>
@@ -46,6 +34,21 @@ public partial struct Country : IEmpty<Country>
     public bool IsEmpty() => !HasValue;
 }
 
+public partial struct Country : IUnknown<Country>
+{
+    /// <summary>False if the country is empty or unknown, otherwise true.</summary>
+    [DebuggerBrowsable(DebuggerBrowsableState.Never)]
+    public bool IsKnown => m_Value != default && m_Value != Unknown.m_Value;
+
+    /// <summary>Returns true if the country is unknown, otherwise false.</summary>
+    [Pure]
+    public bool IsUnknown() => m_Value == Unknown.m_Value;
+
+    /// <summary>Returns true if the country is empty or unknown, otherwise false.</summary>
+    [Pure]
+    public bool IsEmptyOrUnknown() => IsEmpty() || IsUnknown();
+}
+
 public partial struct Country : IEquatable<Country>
 #if NET8_0_OR_GREATER
     , IEqualityOperators<Country, Country, bool>