Wait for "last" event to fire

Question

I need to block execution of my code until a user enters something into a TextBox.

However, in this particular case, I actually need to wait "until the user has finished typing". I.e., I don't want to just wait for the first time that the TextChanged event fires, I want to wait until at least 500ms have passed since the last time it fired before continuing the execution of my method.

Currently I have something that uses timers where every time the TextChanged event fires the timer is restarted and when the timer's Tick event fires it means that the user "has finished typing".

There are three main problems with this approach right now though:

• There has to be a better/cleaner way than using a Timer for this
• Up until now I did not need to block execution until the user "has finished typing", so was basically just adding my code to the Tick event handler, that's not changed though.
• I need to set a timeout as well, so that if the user hasn't finished typing in a certain amount of time, it should just return back to the method as having failed to wait for the user.

How can I accomplish this?

Answer 1

This is very easy to do using ReactiveUI. Look at the example on the main page. It does more or less exactly what you are after.

It is based on Reactive Extensions (RX) for .Net and is written to make things like these easy. If using ReactiveUI is not an option then I suggest you look at RX and how ReactiveUI implements this.