是否需要在WPF MVVM中对ICommand类型的属性使用INotifyPropertyChanged? [英] It is necessary to use INotifyPropertyChanged on properties of type ICommand in WPF MVVM?

问题描述

这两个变量之间是否存在差异(性能，内存泄漏或准则)?

Is there a difference between this two variants (performance, memory leaks or guidelines)?

使用NPC:

private ICommand mGoBackCommand;

    public ICommand GoBackCommand
    {
        get { return mGoBackCommand; }
        set
        {
            if (mGoBackCommand != value)
            {
                mGoBackCommand = value;
                RaisePropertyChanged("GoBackCommand");
            }
        }
    }

自动属性:

public ICommand GoBackCommand {get; set;}

UPD: 最后一个问题是: 如果自动属性是在构造函数中分配一次的简单命令，是否可以在VievModel中使用自动属性，或者由于性能，内存泄漏或其他原因而需要在VM的每个属性上实现NPC?

UPD: Final question is: Can I use auto properties in VievModel if they are simple commands which will be assigned once in constructor, or I need implement NPC on each property of the VM because of performance, memory leaks or something else?

推荐答案

如果您正在编写实现INotifyPropertyChanged的类，则您正在签订的合同规定:任何属性更改时，我都会引发PropertyChanged事件."

If you are writing a class that implements INotifyPropertyChanged, you are making a contract that says "I'll raise the PropertyChanged event when any property changes."

但是，如果您知道某个属性在实例的生存期内不会更改，那么您可以通过不为该属性提高PropertyChanged来琐碎地满足该合同.

But, if you know for a fact that a property won't change during the lifetime of the instance, then you trivially satisfy that contract by never raising PropertyChanged for that property.

因此，如果您在构造函数中一次设置了一个属性(设置为它忘记了"属性)，那么您就不必只为了支持INotifyPropertyChanged而修改该属性，并且可以使用自动实现的财产.但是，在这种情况下，您应该从此更改属性:

So, if you set a property once in the constructor (a "set it a forget it" property), then you don't need to mangle the property just to support INotifyPropertyChanged and you can use an auto-implemented property. However, in this you should change the property from this:

public ICommand GoBackCommand { get; set; }

对此:

public ICommand GoBackCommand { get; private set; }

以免在课堂外意外修改它.

so that it cannot be accidentally modified outside the class.

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