有没有 WinRT iCommand/CommandBinding 实现示例? [英] Any WinRT iCommand/CommandBinding implementaiton samples out there?
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问题描述
将命令抽象到视图模型中是 XAML/MVVM 项目的一项宝贵实践.我明白了.而且,我在 WinRT 中看到了 ICommand;但是,我们如何实施呢?我还没有找到真正有效的样本.有人知道吗?
Abstracting commands into the View Model is a valuable practice with XAML/MVVM projects. I get that. And, I see ICommand in in WinRT; but, how do we implement it? I haven't found a sample that actually works. Anyone know?
推荐答案
我一直以来最喜欢的是 Microsoft 模式和实践团队提供的 DelegateCommand.它允许您创建键入的命令:
My all time favorite has to be the DelegateCommand provided by the Microsoft Patterns and Practices team. It allows you to create a typed command:
MyCommand = new DelegateCommand<MyEntity>(OnExecute);
...
private void OnExecute(MyEntity entity)
{...}
它还提供了一种引发 CanExecuteChanged 事件的方法(以禁用/启用命令)
It also provides a way to raise the CanExecuteChanged event (to disable/enable the command)
MyCommand.RaiseCanExecuteChanged();
代码如下:
public class DelegateCommand<T> : ICommand
{
private readonly Func<T, bool> _canExecuteMethod;
private readonly Action<T> _executeMethod;
#region Constructors
public DelegateCommand(Action<T> executeMethod)
: this(executeMethod, null)
{
}
public DelegateCommand(Action<T> executeMethod, Func<T, bool> canExecuteMethod)
{
_executeMethod = executeMethod;
_canExecuteMethod = canExecuteMethod;
}
#endregion Constructors
#region ICommand Members
public event EventHandler CanExecuteChanged;
bool ICommand.CanExecute(object parameter)
{
try
{
return CanExecute((T)parameter);
}
catch { return false; }
}
void ICommand.Execute(object parameter)
{
Execute((T)parameter);
}
#endregion ICommand Members
#region Public Methods
public bool CanExecute(T parameter)
{
return ((_canExecuteMethod == null) || _canExecuteMethod(parameter));
}
public void Execute(T parameter)
{
if (_executeMethod != null)
{
_executeMethod(parameter);
}
}
public void RaiseCanExecuteChanged()
{
OnCanExecuteChanged(EventArgs.Empty);
}
#endregion Public Methods
#region Protected Methods
protected virtual void OnCanExecuteChanged(EventArgs e)
{
var handler = CanExecuteChanged;
if (handler != null)
{
handler(this, e);
}
}
#endregion Protected Methods
}
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