使用EventHandler更改ToolStripButtomItem属性

Question

this is my first question on stackoverflow, therefore errors in asking-style aren't on purpose.

I'm both, new to C# as to the concept of event-handling, so I would like to know, if there is any possibility to have the value of an ToolStripButtonItem-attribute changed by an EventHandler.

The context is the following:

The code starts by initializing the UI which contains some Windows.Forms- Elements. The ToolStripButtomItem that is of interest for me, has it's Enabled-attribute set to false as default-value. The functionality of this button is to switch into a comparision-view as soon as a certain reference file exists. This allready can be the case when the programm-start, otherwise the reference file might be created during runtime. Of course, you could perform

Button.Enabled=System.IO.File.Exists(Reference-File) 

with the initilization and than do something like

CreateFile(ReferenceFile){
    ...
    Button.Enabled = true;
}

but this seems rather crude to me.

Instead I would like to something like:

Button.Enabled = new System.EventHandler(this.EnableButton);

with

private void EnableButton(Object sender, EventArgs e){
  if(System.IO.FileExists(ReferenceFile)
  Button.Enabled = true; 
}  

What I intend is, to have the button get enabled as soon as the reference-file existst. There are multiple ways to create the reference-file, and there are goint to be even more in the future. To avoid setting the enable-value in each of those createReferenceFile() -Methods, the concept of EventHandling seems quite like the deal to me.

The program I'm trying to run is quite comprehensive, so "polling" is no option at this place.

Answer 1

I suggest to use the FileSystemWatcher and set the enabled property every time it goes of.

    private void StartListening(string path)
    {
        var watch = new FileSystemWatcher();
        watch.Path = path;
        watch.Filter = "*.*";
        watch.Created += UpdateState;
        watch.Deleted += UpdateState;
    }

    void UpdateState(object sender, FileSystemEventArgs e)
    {
        MyButton.Enabled = File.Exists(@"C:\Folder\File.txt");
    }

PS: this is just some very basic example code, you will need to make sure that you have a reference to MyButton and have the correct path there as well ...