式ブロック的なヘルパー。

ExpressionFunc.cs

using System;

namespace Commons {

    /// <remarks>
    /// cf. Proposal: Expression blocks https://github.com/dotnet/csharplang/issues/3086
    /// cf. Proposal: Sequence Expressions https://github.com/dotnet/csharplang/issues/377
    /// </remarks>
    public static class ExpressionFunc {

        public static T With<T>(this T obj, Action<T> action) {
            if (action is null) { throw new ArgumentNullException(nameof(action)); }
            action(obj);
            return obj;
        }

        public static TResult To<T, TResult>(this T obj, Func<T, TResult> func) {
            if (func is null) { throw new ArgumentNullException(nameof(func)); }
            return func(obj);
        }

        public static void With(Action action) {
            if (action is null) { throw new ArgumentNullException(nameof(action)); }
            action();
        }

        public static TResult To<TResult>(Func<TResult> func) {
            if (func is null) { throw new ArgumentNullException(nameof(func)); }
            return func();
        }
    }
}