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?
最佳答案
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)
关于c# - 在实现 INotifyPropertyChanged 时,[CallerMemberName] 是否比替代方案慢?,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/22580623/