TestExpression.cs

#define 有提供存取成員的公開屬性
using System;
using System.Linq;
using System.Linq.Expressions;
using System.Reflection;
using BenchmarkDotNet.Attributes;
using TestDatas;

/*
// * Summary *

BenchmarkDotNet=v0.13.5, OS=Windows 11 (10.0.22621.2715/22H2/2022Update/SunValley2)
12th Gen Intel Core i5-12400, 1 CPU, 12 logical and 6 physical cores
.NET SDK=8.0.100
  [Host]     : .NET 6.0.21 (6.0.2123.36311), X64 RyuJIT AVX2
  DefaultJob : .NET 6.0.21 (6.0.2123.36311), X64 RyuJIT AVX2

|                 Method |       Mean |     Error |    StdDev | Ratio | Rank |   Gen0 | Allocated | Alloc Ratio |
|----------------------- |-----------:|----------:|----------:|------:|-----:|-------:|----------:|------------:|
|     WithPublicProperty |  0.0301 ns | 0.0126 ns | 0.0111 ns | 0.001 |    1 |      - |         - |        0.00 |
| WithExpressionCompiled |  0.6044 ns | 0.0059 ns | 0.0055 ns | 0.025 |    2 |      - |         - |        0.00 |
|         WithReflection | 24.2024 ns | 0.4174 ns | 0.3904 ns | 1.000 |    3 | 0.0025 |      24 B |        1.00 |
*/

namespace Benchmarks
{
    [MemoryDiagnoser]
    [RankColumn]
    public class TestExpression
    {
        MyData _data;
        FieldInfo _fieldInfo;
        Func<MyData, int> _delegate;

        [GlobalSetup]
        public void Setup()
        {
            _data = new MyData(16);

            _fieldInfo = typeof(MyData).GetField("_value", BindingFlags.Instance | BindingFlags.NonPublic);

            var parameter = Expression.Parameter(typeof(MyData));
            var member = Expression.PropertyOrField(parameter, "_value");
            var lambda = Expression.Lambda<Func<MyData, int>>(member, parameter);
            _delegate = lambda.Compile();
        }

#if 有提供存取成員的公開屬性
        [Benchmark]
        public int WithPublicProperty() => _data.Value;
#endif

        [Benchmark]
        public int WithExpressionCompiled() => _delegate(_data);

        [Benchmark(Baseline = true)]
        public int WithReflection() => (int)_fieldInfo.GetValue(_data);
    }
}

namespace TestDatas
{
    public sealed class MyData
    {
        private int _value;

        public MyData(int value) => _value = value;

#if 有提供存取成員的公開屬性
        public int Value
        {
            get => _value;
            set => _value = value;
        }
#endif
    }
}