在 C# 6 之前,属性的初始化不使用支持字段来初始化默认值。在 C#6 中,它使用支持字段通过新的自动初始化属性进行初始化。
我很好奇为什么在 C#6 IL 之前使用属性定义来初始化。这有什么具体原因吗?还是在 C#6 之前没有正确实现?
在 C# 6.0 之前
public class PropertyInitialization
{
public string First { get; set; }
public string Last { get; set; }
public PropertyInitialization()
{
this.First = "Adam";
this.Last = "Smith";
}
}
编译器生成的代码(IL 表示)
public class PropertyInitialisation
{
[CompilerGenerated]
private string \u003CFirst\u003Ek__BackingField;
[CompilerGenerated]
private string \u003CLast\u003Ek__BackingField;
public string First
{
get
{
return this.\u003CFirst\u003Ek__BackingField;
}
set
{
this.\u003CFirst\u003Ek__BackingField = value;
}
}
public string Last
{
get
{
return this.\u003CLast\u003Ek__BackingField;
}
set
{
this.\u003CLast\u003Ek__BackingField = value;
}
}
public PropertyInitialisation()
{
base.\u002Ector();
this.First = "Adam";
this.Last = "Smith";
}
}
C#6
public class AutoPropertyInitialization
{
public string First { get; set; } = "Adam";
public string Last { get; set; } = "Smith";
}
编译器生成的代码(IL 表示)
public class AutoPropertyInitialization
{
[CompilerGenerated]
[DebuggerBrowsable(DebuggerBrowsableState.Never)]
private string \u003CFirst\u003Ek__BackingField;
[CompilerGenerated]
[DebuggerBrowsable(DebuggerBrowsableState.Never)]
private string \u003CLast\u003Ek__BackingField;
public string First
{
get
{
return this.\u003CFirst\u003Ek__BackingField;
}
set
{
this.\u003CFirst\u003Ek__BackingField = value;
}
}
public string Last
{
get
{
return this.\u003CLast\u003Ek__BackingField;
}
set
{
this.\u003CLast\u003Ek__BackingField = value;
}
}
public AutoPropertyInitialization()
{
this.\u003CFirst\u003Ek__BackingField = "Adam";
this.\u003CLast\u003Ek__BackingField = "Smith";
base.\u002Ector();
}
}