c# - 以下在c#中使用expression-bodied语法的方式有区别吗？

Question

public DateTime Date => DateTime.Now;

public DateTime Date { get => DateTime.Now; }

两者之间有区别还是语法不同的等效代码？

Answer 1

两种方式产生相同的 IL。

为了

using System;
public class Program {
    public DateTime MyDate1 { get => DateTime.UtcNow; }
    public DateTime MyDate2 => DateTime.UtcNow;
    public void Main() {
    }
}

两个版本的缩写 IL 是(我使用 https://sharplab.io ):

    // Methods
    .method public hidebysig specialname 
        instance valuetype [mscorlib]System.DateTime get_MyDate1 () cil managed 
    {
        // Method begins at RVA 0x2050
        // Code size 6 (0x6)
        .maxstack 8

        IL_0000: call valuetype [mscorlib]System.DateTime [mscorlib]System.DateTime::get_UtcNow()
        IL_0005: ret
    } // end of method Program::get_MyDate1

    .method public hidebysig specialname 
        instance valuetype [mscorlib]System.DateTime get_MyDate2 () cil managed 
    {
        // Method begins at RVA 0x2050
        // Code size 6 (0x6)
        .maxstack 8

        IL_0000: call valuetype [mscorlib]System.DateTime [mscorlib]System.DateTime::get_UtcNow()
        IL_0005: ret
    } // end of method Program::get_MyDate2

(...)

// Properties
    .property instance valuetype [mscorlib]System.DateTime MyDate1()
    {
        .get instance valuetype [mscorlib]System.DateTime Program::get_MyDate1()
    }
    .property instance valuetype [mscorlib]System.DateTime MyDate2()
    {
        .get instance valuetype [mscorlib]System.DateTime Program::get_MyDate2()
    }