Added functional Apply and Let extension methods, and tests.

Author: MrMatthewLayton

OnixLabs.Core.UnitTests.Data/Mutable.cs

@@ -0,0 +1,20 @@
+// Copyright 2020-2025 ONIXLabs
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+namespace OnixLabs.Core.UnitTests.Data;
+
+public sealed class Mutable
+{
+    public required int Value { get; set; }
+}

OnixLabs.Core.UnitTests/ObjectExtensionTests.cs

@@ -20,34 +20,31 @@ namespace OnixLabs.Core.UnitTests;
 
 public sealed class ObjectExtensionTests
 {
-    [Theory(DisplayName = "IsWithinRangeInclusive should produce the expected result")]
-    [InlineData(2, 1, 3, true)]
-    [InlineData(1, 1, 3, true)]
-    [InlineData(3, 1, 3, true)]
-    [InlineData(0, 1, 3, false)]
-    [InlineData(4, 1, 3, false)]
-    public void IsWithinRangeInclusiveShouldProduceExpectedResult(int value, int min, int max, bool expected)
+    [Fact(DisplayName = "Apply should produce the expected result (reference type)")]
+    public void ApplyShouldProduceExpectedResultReferenceType()
     {
+        // Given
+        Mutable value = new() { Value = 123 };
+
         // When
-        bool actual = value.IsWithinRangeInclusive(min, max);
+        Mutable result = value.Apply(it => it.Value = 456);
 
         // Then
-        Assert.Equal(expected, actual);
+        Assert.Equal(456, value.Value);
+        Assert.Same(value, result);
     }
 
-    [Theory(DisplayName = "IsWithinRangeExclusive should produce the expected result")]
-    [InlineData(2, 1, 3, true)]
-    [InlineData(1, 1, 3, false)]
-    [InlineData(3, 1, 3, false)]
-    [InlineData(0, 1, 3, false)]
-    [InlineData(4, 1, 3, false)]
-    public void IsWithinRangeExclusiveShouldProduceExpectedResult(int value, int min, int max, bool expected)
+    [Fact(DisplayName = "Apply should produce the expected result (value type)")]
+    public void ApplyShouldProduceExpectedResultValueType()
     {
+        // Given
+        int value = 123;
+
         // When
-        bool actual = value.IsWithinRangeExclusive(min, max);
+        value = value.Apply(it => it * 2);
 
         // Then
-        Assert.Equal(expected, actual);
+        Assert.Equal(246, value);
     }
 
     [Fact(DisplayName = "CompareToObject should produce zero if the current IComparable<T> is equal to the specified object.")]
@@ -112,6 +109,51 @@ public void CompareToObjectShouldThrowArgumentExceptionIfSpecifiedObjectIsOfInco
         Assert.Equal("Object must be of type System.Int32 (Parameter 'right')", exception.Message);
     }
 
+    [Theory(DisplayName = "IsWithinRangeInclusive should produce the expected result")]
+    [InlineData(2, 1, 3, true)]
+    [InlineData(1, 1, 3, true)]
+    [InlineData(3, 1, 3, true)]
+    [InlineData(0, 1, 3, false)]
+    [InlineData(4, 1, 3, false)]
+    public void IsWithinRangeInclusiveShouldProduceExpectedResult(int value, int min, int max, bool expected)
+    {
+        // When
+        bool actual = value.IsWithinRangeInclusive(min, max);
+
+        // Then
+        Assert.Equal(expected, actual);
+    }
+
+    [Theory(DisplayName = "IsWithinRangeExclusive should produce the expected result")]
+    [InlineData(2, 1, 3, true)]
+    [InlineData(1, 1, 3, false)]
+    [InlineData(3, 1, 3, false)]
+    [InlineData(0, 1, 3, false)]
+    [InlineData(4, 1, 3, false)]
+    public void IsWithinRangeExclusiveShouldProduceExpectedResult(int value, int min, int max, bool expected)
+    {
+        // When
+        bool actual = value.IsWithinRangeExclusive(min, max);
+
+        // Then
+        Assert.Equal(expected, actual);
+    }
+
+    [Fact(DisplayName = "Let should produce the expected result")]
+    public void LetShouldProduceExpectedResult()
+    {
+        // Given
+        const string value = "123";
+
+        // When
+        int result = value
+            .Let(int.Parse)
+            .Let(it => it * 2);
+
+        // Then
+        Assert.Equal(246, result);
+    }
+
     [Fact(DisplayName = "ToRecordString should produce null when the object is null")]
     public void ToRecordStringShouldProduceNullWhenObjectIsNull()
     {

OnixLabs.Core/Extensions.Object.cs

@@ -41,32 +41,31 @@ public static class ObjectExtensions
     private const string ObjectPropertyAssignment = " = ";
 
     /// <summary>
-    /// Determines whether the current <see cref="IComparable{T}"/> value falls within range, inclusive of the specified minimum and maximum values.
+    /// Calls the specified <see cref="Action{T}"/> with the current <paramref name="value"/>.
     /// </summary>
-    /// <param name="value">The value to test.</param>
-    /// <param name="min">The inclusive minimum value.</param>
-    /// <param name="max">The inclusive maximum value.</param>
-    /// <typeparam name="T">The underlying <see cref="IComparable{T}"/> type.</typeparam>
-    /// <returns>
-    /// Returns <see langword="true"/> if the current <see cref="IComparable{T}"/> value falls within range,
-    /// inclusive of the specified minimum and maximum values; otherwise, <see langword="false"/>.
-    /// </returns>
-    public static bool IsWithinRangeInclusive<T>(this T value, T min, T max) where T : IComparable<T> =>
-        value.CompareTo(min) is 0 or 1 && value.CompareTo(max) is 0 or -1;
+    /// <param name="value">The value to pass to the specified <see cref="Action{T}"/>.</param>
+    /// <param name="action">The action into which the current <paramref name="value"/> will be passed.</param>
+    /// <typeparam name="T">The underlying type of the current value.</typeparam>
+    /// <returns>Returns the current <paramref name="value"/> once the specified <see cref="Action{T}"/> has been executed.</returns>
+    public static T Apply<T>(this T value, Action<T> action) where T : class
+    {
+        RequireNotNull(action, "Action must not be null.", nameof(action));
+        action(value);
+        return value;
+    }
 
     /// <summary>
-    /// Determines whether the current <see cref="IComparable{T}"/> value falls within range, exclusive of the specified minimum and maximum values.
+    /// Calls the specified <see cref="Func{T, TResult}"/> with the current <paramref name="value"/>.
     /// </summary>
-    /// <param name="value">The value to test.</param>
-    /// <param name="min">The exclusive minimum value.</param>
-    /// <param name="max">The exclusive maximum value.</param>
-    /// <typeparam name="T">The underlying <see cref="IComparable{T}"/> type.</typeparam>
-    /// <returns>
-    /// Returns <see langword="true"/> if the current <see cref="IComparable{T}"/> value falls within range,
-    /// exclusive of the specified minimum and maximum values; otherwise, <see langword="false"/>.
-    /// </returns>
-    public static bool IsWithinRangeExclusive<T>(this T value, T min, T max) where T : IComparable<T> =>
-        value.CompareTo(min) is 1 && value.CompareTo(max) is -1;
+    /// <param name="value">The value to pass to the specified <see cref="Func{T, TResult}"/>.</param>
+    /// <param name="function">The function into which the current <paramref name="value"/> will be passed.</param>
+    /// <typeparam name="T">The underlying type of the current value.</typeparam>
+    /// <returns>Returns the result of the specified <see cref="Func{T, TResult}"/>.</returns>
+    public static T Apply<T>(this T value, Func<T, T> function) where T : struct
+    {
+        RequireNotNull(function, "Function must not be null.", nameof(function));
+        return function(value);
+    }
 
     /// <summary>
     /// Compares the current <typeparamref name="T"/> instance with the specified <typeparamref name="T"/> instance.
@@ -108,6 +107,48 @@ public static int CompareToNullable<T>(this T left, T? right) where T : struct,
         _ => throw new ArgumentException($"Object must be of type {typeof(T).FullName}", nameof(right))
     };
 
+    /// <summary>
+    /// Determines whether the current <see cref="IComparable{T}"/> value falls within range, inclusive of the specified minimum and maximum values.
+    /// </summary>
+    /// <param name="value">The value to test.</param>
+    /// <param name="min">The inclusive minimum value.</param>
+    /// <param name="max">The inclusive maximum value.</param>
+    /// <typeparam name="T">The underlying <see cref="IComparable{T}"/> type.</typeparam>
+    /// <returns>
+    /// Returns <see langword="true"/> if the current <see cref="IComparable{T}"/> value falls within range,
+    /// inclusive of the specified minimum and maximum values; otherwise, <see langword="false"/>.
+    /// </returns>
+    public static bool IsWithinRangeInclusive<T>(this T value, T min, T max) where T : IComparable<T> =>
+        value.CompareTo(min) is 0 or 1 && value.CompareTo(max) is 0 or -1;
+
+    /// <summary>
+    /// Determines whether the current <see cref="IComparable{T}"/> value falls within range, exclusive of the specified minimum and maximum values.
+    /// </summary>
+    /// <param name="value">The value to test.</param>
+    /// <param name="min">The exclusive minimum value.</param>
+    /// <param name="max">The exclusive maximum value.</param>
+    /// <typeparam name="T">The underlying <see cref="IComparable{T}"/> type.</typeparam>
+    /// <returns>
+    /// Returns <see langword="true"/> if the current <see cref="IComparable{T}"/> value falls within range,
+    /// exclusive of the specified minimum and maximum values; otherwise, <see langword="false"/>.
+    /// </returns>
+    public static bool IsWithinRangeExclusive<T>(this T value, T min, T max) where T : IComparable<T> =>
+        value.CompareTo(min) is 1 && value.CompareTo(max) is -1;
+
+    /// <summary>
+    /// Calls the specified <see cref="Func{T, TResult}"/> with the current <paramref name="value"/> as its argument and returns the result.
+    /// </summary>
+    /// <param name="value">The value to pass to the specified <see cref="Func{T, TResult}"/>.</param>
+    /// <param name="function">The function into which the current <paramref name="value"/> will be passed.</param>
+    /// <typeparam name="TSource">The underlying type of the current value.</typeparam>
+    /// <typeparam name="TResult">The underlying type of the result value.</typeparam>
+    /// <returns>Returns the result of the specified <see cref="Func{T, TResult}"/>.</returns>
+    public static TResult Let<TSource, TResult>(this TSource value, Func<TSource, TResult> function)
+    {
+        RequireNotNull(function, "Function must not be null.", nameof(function));
+        return function(value);
+    }
+
     /// <summary>
     /// Gets a record-like <see cref="String"/> representation of the current <see cref="Object"/> instance.
     /// <remarks>This method is designed specifically for record-like objects and may produce undesirable results when applied to primitive-like objects.</remarks>