从另一个方法访问变量 [英] Access a variable from another method

问题描述

我无法从其他方法访问FileSystemWatcher。

I am having trouble accessing a FileSystemWatcher from another method.

public static void watch(string path)
{
    FileSystemWatcher watcher = new FileSystemWatcher();

    watcher.Path = path;
    watcher.NotifyFilter = NotifyFilters.Attributes |
                   NotifyFilters.CreationTime |
                   NotifyFilters.DirectoryName |
                   NotifyFilters.FileName |
                   NotifyFilters.LastAccess |
                   NotifyFilters.LastWrite |
                   NotifyFilters.Security |
                   NotifyFilters.Size;
    watcher.Filter = "*.*";
    watcher.IncludeSubdirectories = true;
    watcher.Changed += new FileSystemEventHandler(OnChanged);
    watcher.Created += new FileSystemEventHandler(OnChanged);
    watcher.Deleted += new FileSystemEventHandler(OnChanged);
    watcher.Renamed += new RenamedEventHandler(OnChanged);
    watcher.EnableRaisingEvents = true;
}

private static void OnChanged(object sender, FileSystemEventArgs e)
{
    // The reason for having this try block (and EnableRaisingEvents toggling)
    // is to solve a known problem with FileSystemWatcher, in which the event
    // is fired twice.

    try
    {
        MessageBox.Show("File changed.");

        watcher.EnableRaisingEvents = false; // Error: The name 'watcher' does
                                            // not exist in the current context
    }
    finally
    {
        watcher.EnableRaisingEvents = true; // Error: The name 'watcher' does
                                           // not exist in the current context
    }
}

我想更改EnableRaisingEvents属性。



由于范围问题我无法做到这一点。通常我会做的是在一个范围更大的地方声明FileSystemWatcher，但我不能在这里做，因为每次运行方法时都必须创建一个新的。



那么，如何从不同的方法更改对象的属性？



PS：我已经搜索了周围，尝试了不同的东西，但最终没有任何效果。



编辑：只是为了澄清，我必须保留FileSystemWatcher声明INSIDE方法（而不是给它一个更大的范围，从而允许通过另一种方法进行修改）。原因是我每次运行方法时都需要创建一个新的。

I want to change the EnableRaisingEvents property.

I can't do that because of the scope problem. Normally what I would do is declare the FileSystemWatcher somewhere with a bigger scope, but I can't do that here because a new one must be created every time I run the method.

So, how can I change the property of an object from a different method?

PS: I have searched around, and tried different things but ultimately nothing worked.

Just to clarify, I MUST keep the FileSystemWatcher declaration INSIDE the method (as opposed to giving it a bigger scope, thus allowing it to be modified by another method). The reason for this is that I need a new one to be created every time I run the method.

推荐答案

我很确定<在 watch 方法中创建的code> FileSystemWatcher 将是 sender OnChanged 方法的参数。

在这种情况下，它应该非常简单：



I'm pretty sure that the FileSystemWatcher created in the watch method will be the value of the sender parameter of the OnChanged method.
In that case, it should be pretty simple:

private static void OnChanged(object sender, FileSystemEventArgs e)
{
    FileSystemWatcher watcher = sender as FileSystemWatcher;
    if (watcher == null)      // sender isn't a FileSystemWatcher
      return;                 // quit while we're behind! :-)

    // The reason for having this try block (and EnableRaisingEvents toggling)
    // is to solve a known problem with FileSystemWatcher, in which the event
    // is fired twice.

    try
    {
        MessageBox.Show("File changed.");

        watcher.EnableRaisingEvents = false; // Error: The name 'watcher' does
                                             // not exist in the current context
    }
    finally
    {
        watcher.EnableRaisingEvents = true; // Error: The name 'watcher' does
                                            // not exist in the current context
    }
}

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