修复 RelayCommand 中可能存在的内存泄漏

Question

使用内存分析器并比较快照，我们发现 150 多个 RelayCommand 类型的对象在快照之间存活而不是被释放。

RelayCommand 在快照之间注册，然后取消注册。

注销过程是否完成？

还有其他与RelayCommand相关的资源要释放吗？

中继命令代码：

public class RelayCommand : ICommand
{
    #region Fields

    readonly Action<object> _execute;
    readonly Predicate<object> _canExecute;

    #endregion // Fields

    #region Constructors

    /// <summary>
    /// Creates a new command that can always execute.
    /// </summary>
    /// <param name="execute">The execution logic.</param>
    public RelayCommand(Action<object> execute)
        : this(execute, null)
    {
    }

    /// <summary>
    /// Creates a new command.
    /// </summary>
    /// <param name="execute">The execution logic.</param>
    /// <param name="canExecute">The execution status logic.</param>
    public RelayCommand(Action<object> execute, Predicate<object> canExecute)
    {
        if (execute == null)
            throw new ArgumentNullException("execute");

        _execute = execute;
        _canExecute = canExecute;
    }

    #endregion // Constructors

    #region ICommand Members

    [DebuggerStepThrough]
    public bool CanExecute(object parameter)
    {
        return _canExecute == null ? true : _canExecute(parameter);
    }

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

    public void Execute(object parameter)
    {
        this._execute(parameter);
    }

    #endregion // ICommand Members
}

Answer 1

RequerySuggested 持有弱引用并且不会阻止对象被释放，因此它不是问题的根源。如果内存影响不可接受，请尽量减少创建的命令实例的数量。