Class OneOfExtensions

Namespace: REslava.Result.AdvancedPatterns

Assembly: REslava.Result.dll

Extension methods for OneOf types, providing conversion between 2-way through 6-way OneOf instances.

public static class OneOfExtensions

Inheritance: object

OneOfExtensions

Inherited Members: object.Equals(object)

object.Equals(object, object)

object.GetHashCode()

object.GetType()

object.MemberwiseClone()

object.ReferenceEquals(object, object)

object.ToString()

Remarks

These extension methods provide explicit, type-safe conversions across the full OneOf arity chain: OneOf<T1,T2> ↔ OneOf<T1,T2,T3> ↔ OneOf<T1,T2,T3,T4> ↔ OneOf<T1,T2,T3,T4,T5> ↔ OneOf<T1,T2,T3,T4,T5,T6>. All conversions are explicit to ensure developers make conscious decisions about how to handle the additional type.

The design philosophy is explicit over implicit - conversions require developers to specify how to handle the removed type, preventing accidental data loss or unexpected behavior.

Methods

ToFiveWayWithFallback<T1, T2, T3, T4, T5, T6>(OneOf<T1, T2, T3, T4, T5, T6>, T1?, T2?, T3?, T4?, T5?)

Converts a 6-way OneOf to a 5-way OneOf by replacing the T6 case with a fallback value.

public static OneOf<T1, T2, T3, T4, T5> ToFiveWayWithFallback<T1, T2, T3, T4, T5, T6>(this OneOf<T1, T2, T3, T4, T5, T6> oneOf, T1? fallbackT1 = null, T2? fallbackT2 = null, T3? fallbackT3 = null, T4? fallbackT4 = null, T5? fallbackT5 = null) where T1 : class where T2 : class where T3 : class where T4 : class where T5 : class

Parameters

oneOf OneOf<T1, T2, T3, T4, T5, T6>
fallbackT1 T1
fallbackT2 T2
fallbackT3 T3
fallbackT4 T4
fallbackT5 T5

Returns

OneOf<T1, T2, T3, T4, T5>

Type Parameters

T1
T2
T3
T4
T5
T6

ToFiveWay<T1, T2, T3, T4, T5>(OneOf<T1, T2, T3, T4>, T5)

Converts a 4-way OneOf to a 5-way OneOf by providing a default value for the fifth type.

public static OneOf<T1, T2, T3, T4, T5> ToFiveWay<T1, T2, T3, T4, T5>(this OneOf<T1, T2, T3, T4> oneOf, T5 defaultValue)

Parameters

oneOf OneOf<T1, T2, T3, T4>: The 4-way OneOf to convert.
defaultValue T5: Anchors the T5 type parameter; not used at runtime.

Returns

OneOf<T1, T2, T3, T4, T5>

Type Parameters

T1
T2
T3
T4
T5

ToFiveWay<T1, T2, T3, T4, T5, T6>(OneOf<T1, T2, T3, T4, T5, T6>)

Converts a 6-way OneOf to a 5-way OneOf, returning null when the value is T6.

public static OneOf<T1, T2, T3, T4, T5>? ToFiveWay<T1, T2, T3, T4, T5, T6>(this OneOf<T1, T2, T3, T4, T5, T6> oneOf)

Parameters

oneOf OneOf<T1, T2, T3, T4, T5, T6>

Returns

OneOf<T1, T2, T3, T4, T5>?

Type Parameters

T1
T2
T3
T4
T5
T6

ToFiveWay<T1, T2, T3, T4, T5, T6>(OneOf<T1, T2, T3, T4, T5, T6>, Func<T6, T1>?, Func<T6, T2>?, Func<T6, T3>?, Func<T6, T4>?, Func<T6, T5>?)

Converts a 6-way OneOf to a 5-way OneOf by mapping the T6 case to one of the first five types.

public static OneOf<T1, T2, T3, T4, T5> ToFiveWay<T1, T2, T3, T4, T5, T6>(this OneOf<T1, T2, T3, T4, T5, T6> oneOf, Func<T6, T1>? t6ToT1 = null, Func<T6, T2>? t6ToT2 = null, Func<T6, T3>? t6ToT3 = null, Func<T6, T4>? t6ToT4 = null, Func<T6, T5>? t6ToT5 = null)

Parameters

oneOf OneOf<T1, T2, T3, T4, T5, T6>
t6ToT1 Func<T6, T1>
t6ToT2 Func<T6, T2>
t6ToT3 Func<T6, T3>
t6ToT4 Func<T6, T4>
t6ToT5 Func<T6, T5>

Returns

OneOf<T1, T2, T3, T4, T5>

Type Parameters

T1
T2
T3
T4
T5
T6

ToFourWayWithFallback<T1, T2, T3, T4, T5>(OneOf<T1, T2, T3, T4, T5>, T1?, T2?, T3?, T4?)

Converts a 5-way OneOf to a 4-way OneOf by replacing the T5 case with a fallback value.

public static OneOf<T1, T2, T3, T4> ToFourWayWithFallback<T1, T2, T3, T4, T5>(this OneOf<T1, T2, T3, T4, T5> oneOf, T1? fallbackT1 = null, T2? fallbackT2 = null, T3? fallbackT3 = null, T4? fallbackT4 = null) where T1 : class where T2 : class where T3 : class where T4 : class

Parameters

oneOf OneOf<T1, T2, T3, T4, T5>
fallbackT1 T1
fallbackT2 T2
fallbackT3 T3
fallbackT4 T4

Returns

OneOf<T1, T2, T3, T4>

Type Parameters

T1
T2
T3
T4
T5

ToFourWay<T1, T2, T3, T4>(OneOf<T1, T2, T3>, T4)

Converts a 3-way OneOf to a 4-way OneOf by providing a default value for the fourth type.

public static OneOf<T1, T2, T3, T4> ToFourWay<T1, T2, T3, T4>(this OneOf<T1, T2, T3> oneOf, T4 defaultValue)

Parameters

oneOf OneOf<T1, T2, T3>: The 3-way OneOf to convert.
defaultValue T4: Anchors the T4 type parameter; not used at runtime.

Returns

OneOf<T1, T2, T3, T4>

Type Parameters

T1
T2
T3
T4

ToFourWay<T1, T2, T3, T4, T5>(OneOf<T1, T2, T3, T4, T5>)

Converts a 5-way OneOf to a 4-way OneOf, returning null when the value is T5.

public static OneOf<T1, T2, T3, T4>? ToFourWay<T1, T2, T3, T4, T5>(this OneOf<T1, T2, T3, T4, T5> oneOf)

Parameters

oneOf OneOf<T1, T2, T3, T4, T5>

Returns

OneOf<T1, T2, T3, T4>?

Type Parameters

T1
T2
T3
T4
T5

ToFourWay<T1, T2, T3, T4, T5>(OneOf<T1, T2, T3, T4, T5>, Func<T5, T1>?, Func<T5, T2>?, Func<T5, T3>?, Func<T5, T4>?)

Converts a 5-way OneOf to a 4-way OneOf by mapping the T5 case to one of the first four types.

public static OneOf<T1, T2, T3, T4> ToFourWay<T1, T2, T3, T4, T5>(this OneOf<T1, T2, T3, T4, T5> oneOf, Func<T5, T1>? t5ToT1 = null, Func<T5, T2>? t5ToT2 = null, Func<T5, T3>? t5ToT3 = null, Func<T5, T4>? t5ToT4 = null)

Parameters

oneOf OneOf<T1, T2, T3, T4, T5>
t5ToT1 Func<T5, T1>
t5ToT2 Func<T5, T2>
t5ToT3 Func<T5, T3>
t5ToT4 Func<T5, T4>

Returns

OneOf<T1, T2, T3, T4>

Type Parameters

T1
T2
T3
T4
T5

ToSixWay<T1, T2, T3, T4, T5, T6>(OneOf<T1, T2, T3, T4, T5>, T6)

Converts a 5-way OneOf to a 6-way OneOf by providing a default value for the sixth type.

public static OneOf<T1, T2, T3, T4, T5, T6> ToSixWay<T1, T2, T3, T4, T5, T6>(this OneOf<T1, T2, T3, T4, T5> oneOf, T6 defaultValue)

Parameters

oneOf OneOf<T1, T2, T3, T4, T5>: The 5-way OneOf to convert.
defaultValue T6: Anchors the T6 type parameter; not used at runtime.

Returns

OneOf<T1, T2, T3, T4, T5, T6>

Type Parameters

T1
T2
T3
T4
T5
T6

ToThreeWayWithFallback<T1, T2, T3, T4>(OneOf<T1, T2, T3, T4>, T1?, T2?, T3?)

Converts a 4-way OneOf to a 3-way OneOf by replacing the T4 case with a fallback value.

public static OneOf<T1, T2, T3> ToThreeWayWithFallback<T1, T2, T3, T4>(this OneOf<T1, T2, T3, T4> oneOf, T1? fallbackT1 = null, T2? fallbackT2 = null, T3? fallbackT3 = null) where T1 : class where T2 : class where T3 : class

Parameters

oneOf OneOf<T1, T2, T3, T4>
fallbackT1 T1
fallbackT2 T2
fallbackT3 T3

Returns

OneOf<T1, T2, T3>

Type Parameters

T1
T2
T3
T4

ToThreeWay<T1, T2, T3>(OneOf<T1, T2>, T3)

Converts a 2-way OneOf to a 3-way OneOf by providing a default value for the third type.

public static OneOf<T1, T2, T3> ToThreeWay<T1, T2, T3>(this OneOf<T1, T2> oneOf, T3 defaultValue)

Parameters

oneOf OneOf<T1, T2>: The 2-way OneOf to convert.
defaultValue T3: The default value to use if the 3-way OneOf needs to represent T3.

Returns

OneOf<T1, T2, T3>: A 3-way OneOf containing the original value or the default for T3.

Type Parameters

T1: The first type.
T2: The second type.
T3: The third type.

Examples

OneOf<Error, Success> twoWay = new Success("Data processed");
OneOf<Error, Success, Warning> threeWay = twoWay.ToThreeWay<Warning>(new Warning("No warnings"));

Remarks

This conversion is safe and preserves the original value. The default value is only used when the 3-way OneOf needs to represent a T3 value in other operations.

ToThreeWay<T1, T2, T3, T4>(OneOf<T1, T2, T3, T4>)

Converts a 4-way OneOf to a 3-way OneOf, returning null when the value is T4.

public static OneOf<T1, T2, T3>? ToThreeWay<T1, T2, T3, T4>(this OneOf<T1, T2, T3, T4> oneOf)

Parameters

oneOf OneOf<T1, T2, T3, T4>

Returns

OneOf<T1, T2, T3>?

Type Parameters

T1
T2
T3
T4

ToThreeWay<T1, T2, T3, T4>(OneOf<T1, T2, T3, T4>, Func<T4, T1>?, Func<T4, T2>?, Func<T4, T3>?)

Converts a 4-way OneOf to a 3-way OneOf by mapping the T4 case to one of the first three types.

public static OneOf<T1, T2, T3> ToThreeWay<T1, T2, T3, T4>(this OneOf<T1, T2, T3, T4> oneOf, Func<T4, T1>? t4ToT1 = null, Func<T4, T2>? t4ToT2 = null, Func<T4, T3>? t4ToT3 = null)

Parameters

oneOf OneOf<T1, T2, T3, T4>
t4ToT1 Func<T4, T1>
t4ToT2 Func<T4, T2>
t4ToT3 Func<T4, T3>

Returns

OneOf<T1, T2, T3>

Type Parameters

T1
T2
T3
T4

ToTwoWayWithFallback<T1, T2, T3>(OneOf<T1, T2, T3>, T1?, T2?)

Converts a 3-way OneOf to a 2-way OneOf by providing a fallback value for the third type.

public static OneOf<T1, T2> ToTwoWayWithFallback<T1, T2, T3>(this OneOf<T1, T2, T3> oneOf, T1? fallbackT1 = null, T2? fallbackT2 = null) where T1 : class where T2 : class

Parameters

oneOf OneOf<T1, T2, T3>: The 3-way OneOf to convert.
fallbackT1 T1: Fallback T1 value when the OneOf contains T3.
fallbackT2 T2: Fallback T2 value when the OneOf contains T3.

Returns

OneOf<T1, T2>: A 2-way OneOf with T3 replaced by the specified fallback.

Type Parameters

T1: The first type.
T2: The second type.
T3: The third type.

Examples

OneOf<Error, Success, Warning> threeWay = new Warning("Deprecated API");
OneOf<Error, Success> twoWay = threeWay.ToTwoWayWithFallback(
    fallbackT1: new Error("Warning occurred"),
    fallbackT2: new Success("Warning handled")
);

Remarks

This conversion allows you to handle the T3 case by replacing it with a fallback value. You must provide at least one fallback value. If both are provided, fallbackT1 takes precedence.

Exceptions

ArgumentException: Thrown when both fallback values are null.

ToTwoWay<T1, T2, T3>(OneOf<T1, T2, T3>)

Converts a 3-way OneOf to a 2-way OneOf by filtering out the third type.

public static OneOf<T1, T2>? ToTwoWay<T1, T2, T3>(this OneOf<T1, T2, T3> oneOf)

Parameters

oneOf OneOf<T1, T2, T3>: The 3-way OneOf to convert.

Returns

OneOf<T1, T2>?: A 2-way OneOf if the original contains T1 or T2, null if it contains T3.

Type Parameters

T1: The first type.
T2: The second type.
T3: The third type to filter out.

Examples

OneOf<Error, Success, Warning> threeWay = new Success("Data processed");
OneOf<Error, Success>? twoWay = threeWay.ToTwoWay<Error, Success, Warning>();
if (twoWay.HasValue) { /* process T1/T2 case */ }

Remarks

This conversion filters out the T3 case. If the 3-way OneOf contains T3, the result is null to indicate that the value couldn't be represented in the 2-way type system. This explicit null return makes it clear that data might be lost in the conversion.

ToTwoWay<T1, T2, T3>(OneOf<T1, T2, T3>, Func<T3, T1>?, Func<T3, T2>?)

Converts a 3-way OneOf to a 2-way OneOf by mapping the third type to one of the first two.

public static OneOf<T1, T2> ToTwoWay<T1, T2, T3>(this OneOf<T1, T2, T3> oneOf, Func<T3, T1>? t3ToT1 = null, Func<T3, T2>? t3ToT2 = null)

Parameters

oneOf OneOf<T1, T2, T3>: The 3-way OneOf to convert.
t3ToT1 Func<T3, T1>: Function to convert T3 to T1 when needed.
t3ToT2 Func<T3, T2>: Function to convert T3 to T2 when needed.

Returns

OneOf<T1, T2>: A 2-way OneOf with T3 mapped to either T1 or T2.

Type Parameters

T1: The first type.
T2: The second type.
T3: The third type to map.

Examples

OneOf<Error, Success, Warning> threeWay = new Warning("Deprecated API");
OneOf<Error, Success> twoWay = threeWay.ToTwoWay(
    t3ToT1: warning => new Error($"Warning: {warning.Message}"),
    t3ToT2: warning => new Success($"Warning handled: {warning.Message}")
);

Remarks

This conversion allows you to handle the T3 case by mapping it to either T1 or T2. You must provide at least one mapping function to handle the T3 case. If both functions are provided, t3ToT1 takes precedence.

Exceptions

ArgumentNullException: Thrown when both mapping functions are null.