Delegatecommand，relaycommand和routed命令之间的差异

问题描述

我对命令模式感到困惑。有关命令有这么多不同的解释。我认为下面的代码是delegatecommand，但在阅读了关于relaycommand后，我有疑问。

I'm confused about command pattern. There are so many different explanations about the commands. I thought the code below was delegatecommand, but after reading about the relaycommand, I am in doubt.

relaycommand，delegatecommand和routedcommand之间的区别是什么。是否可以在与我发布的代码相关的示例中显示？

What is the difference between relaycommand, delegatecommand and routedcommand. Is it possible to show in examples that have relevance to my posted code?

class FindProductCommand : ICommand
{
    ProductViewModel _avm;

    public FindProductCommand(ProductViewModel avm)
    {
        _avm = avm;
    }

    public bool CanExecute(object parameter)
    {
        return _avm.CanFindProduct();
    }

    public void Execute(object parameter)
    {
        _avm.FindProduct();
    }

    public event EventHandler CanExecuteChanged
    {
        add { CommandManager.RequerySuggested += value; }
        remove { CommandManager.RequerySuggested -= value; }
    }

}

推荐答案

您的类是 FindProductCommand ，它实现了接口 ICommand ，因此可以用作WPF command 。它既不是 DelegateCommand 也不是 RelayCommand ，也不是 RoutedCommand ，这是 ICommand 接口的其他实现。

Your class is a FindProductCommand which implements the interface ICommand so it can be used as a WPF command. It is neither a DelegateCommand nor a RelayCommand, nor is it a RoutedCommand, which are other implementations of the ICommand interface.

通常， $ c> ICommand 命名为 DelegateCommand 或 RelayCommand ，意图是您不应必须实现 ICommand 接口，而是将必要的方法作为参数传递给 DelegateCommand / RelayCommand 构造函数。而不是整个类，你可以写：

Generally, when an implementation of ICommand is named DelegateCommand or RelayCommand, the intention is that you should not have to implement the ICommand interface, but rather pass the necessary methods as parameters to the DelegateCommand / RelayCommand constructor. Instead of your entire class, you could write:

ProductViewModel _avm;
var FindPoductCommand = new DelegateCommand<object>(
    (parameter) => _avm.FindProduct(),
    (parameter) => _avm.CanFindProduct()
);

至于RoutedCommand和RelayCommand / DelegateCommand之间的区别，请参阅。

As far as the difference between RoutedCommand and RelayCommand/DelegateCommand, see here.

• 
  
• 也称为 DelegateCommand


• 的原始实现

• Microsoft Prism DelegateCommand reference
• WPF Tutorial implementation of ICommand called DelegateCommand
• Another implementation also called DelegateCommand
• The original implementation of RelayCommand by Josh Smith

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