function to wait for a variable to change value

waitfor(h,'PropertyName') as this syntax blocks the caller from executing until the value of 'PropertyName' (any property of the graphics object h) changes or h closes (is deleted), Is there any similar syntax that can suspend the command and wait until a variable changes its value?

Thanks!

Answer 1

[Walter Roberson]

It took me a bit of time to come up with a mechanism by which such a situation could happen at all (if one leaves out parallel processing.)

In every case I have been able to think of, there has to be a callback involved (whether handle graphics or timer or serial object or the like.) Without parallel processing, callbacks are the only mechanism to (however temporarily) get a second thread going that can do independent work such as changing a variable. And if you are going to have a callback involved, one might as well wait on a graphics object property that stands proxy for the variable being changed.

For example, in various callbacks, one might have

set(0,'UserData','X71_Updated');

set(0,'UserData','Theta_Updated');

set(0,'UserData','23Skidoo_Updated');

and then at a point where you were interested in knowing that your variable had changed, you could

waitfor(0,'Userdata','23Skidoo_Updated');