c# - 在实现 INotifyPropertyChanged 时，[CallerMemberName] 是否比替代方案慢？

Question

有好文章推荐different ways for implementing INotifyPropertyChanged .

考虑以下基本实现:

class BasicClass : INotifyPropertyChanged
{
    public event PropertyChangedEventHandler PropertyChanged;

    private void FirePropertyChanged(string propertyName)
    {
        var handler = PropertyChanged;
        if (handler != null)
            handler(this, new PropertyChangedEventArgs(propertyName));
    }

    private int sampleIntField;

    public int SampleIntProperty
    {
        get { return sampleIntField; }
        set
        {
            if (value != sampleIntField)
            {
                sampleIntField = value;
                FirePropertyChanged("SampleIntProperty"); // ouch ! magic string here
            }
        }
    }
}

我想用这个替换它:

using System.Runtime.CompilerServices;

class BetterClass : INotifyPropertyChanged
{
    public event PropertyChangedEventHandler PropertyChanged;
    // Check the attribute in the following line :
    private void FirePropertyChanged([CallerMemberName] string propertyName = null)
    {
        var handler = PropertyChanged;
        if (handler != null)
            handler(this, new PropertyChangedEventArgs(propertyName));
    }

    private int sampleIntField;

    public int SampleIntProperty
    {
        get { return sampleIntField; }
        set
        {
            if (value != sampleIntField)
            {
                sampleIntField = value;
                // no "magic string" in the following line :
                FirePropertyChanged();
            }
        }
    }
}

但有时我读到，与替代项相比，[CallerMemberName] 属性的性能较差。这是真的吗？为什么？它使用反射吗？

Answer 1

不，使用[CallerMemberName]并不比上面的基本实现慢。

这是因为，根据 this MSDN page ,

Caller Info values are emitted as literals into the Intermediate Language (IL) at compile time

我们可以使用任何 IL 反汇编程序(如 ILSpy)进行检查:属性的“SET”操作代码的编译方式完全相同:

所以这里没有使用反射。

(使用VS2013编译的示例)