Object - IfNotNull

A T extension method that execute an action when the value is not null.

public static void Main()
{
    var values = new List<string> { "Fizz", "Buzz" };
    List<string> valuesNull = null;
    string actionOutput1 = null;
    string actionOutput2 = null;

    // C# Extension Method: Object - IfNotNull
    string result1 = values.IfNotNull(x => x.First(), "FizzBuzz"); // return "Fizz";
    string result2 = valuesNull.IfNotNull(x => x.First(), "FizzBuzz"); // return "FizzBuzz";
    string result3 = valuesNull.IfNotNull(x => x.First(), () => "FizzBuzz"); // return "FizzBuzz"

    values.IfNotNull(x => actionOutput1 = string.Join("", values)); // = "FizzBuzz"
    valuesNull.IfNotNull(x => actionOutput2 = string.Join("", values)); // Do Nothing

    Console.WriteLine(result1);
    Console.WriteLine(result2);
    Console.WriteLine(result3);

    Console.WriteLine(actionOutput1);
    Console.WriteLine(actionOutput2);
}

View Source

using System;

public static partial class Extensions
{
    /// <summary>A T extension method that execute an action when the value is not null.</summary>
    /// <typeparam name="T">Generic type parameter.</typeparam>
    /// <param name="this">The @this to act on.</param>
    /// <param name="action">The action.</param>
    public static void IfNotNull<T>(this T @this, Action<T> action) where T : class
    {
        if (@this != null)
        {
            action(@this);
        }
    }

    /// <summary>
    ///     A T extension method that the function result if not null otherwise default value.
    /// </summary>
    /// <typeparam name="T">Generic type parameter.</typeparam>
    /// <typeparam name="TResult">Type of the result.</typeparam>
    /// <param name="this">The @this to act on.</param>
    /// <param name="func">The function.</param>
    /// <returns>The function result if @this is not null otherwise default value.</returns>
    public static TResult IfNotNull<T, TResult>(this T @this, Func<T, TResult> func) where T : class
    {
        return @this != null ? func(@this) : default(TResult);
    }

    /// <summary>
    ///     A T extension method that the function result if not null otherwise default value.
    /// </summary>
    /// <typeparam name="T">Generic type parameter.</typeparam>
    /// <typeparam name="TResult">Type of the result.</typeparam>
    /// <param name="this">The @this to act on.</param>
    /// <param name="func">The function.</param>
    /// <param name="defaultValue">The default value.</param>
    /// <returns>The function result if @this is not null otherwise default value.</returns>
    public static TResult IfNotNull<T, TResult>(this T @this, Func<T, TResult> func, TResult defaultValue) where T : class
    {
        return @this != null ? func(@this) : defaultValue;
    }

    /// <summary>
    ///     A T extension method that the function result if not null otherwise default value.
    /// </summary>
    /// <typeparam name="T">Generic type parameter.</typeparam>
    /// <typeparam name="TResult">Type of the result.</typeparam>
    /// <param name="this">The @this to act on.</param>
    /// <param name="func">The function.</param>
    /// <param name="defaultValueFactory">The default value factory.</param>
    /// <returns>The function result if @this is not null otherwise default value.</returns>
    public static TResult IfNotNull<T, TResult>(this T @this, Func<T, TResult> func, Func<TResult> defaultValueFactory) where T : class
    {
        return @this != null ? func(@this) : defaultValueFactory();
    }
}