Problem with timers in a GUI

2020 9 30
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更新时间：2020 9 30
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I have a GUI in which I create and start a bunch of timers during the startupFcn. Frequently I get the following error:
Error while evaluating TimerFcn for timer 'statusUpdateTimer'
Trying to load file "<filename>.mlapp" while it is being loaded.
It seems to happen more frequently if the timer is started at the end of the constructor, but I've also seen it at other times (ie not just during construction) on timer callbacks when other GUI operations are running.
What does the error mean and how can I eliminate it?

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Adam Danz
Adam Danz 2020-9-30
What does the TimerFcn do? It sounds like there may be some recursion.
Do all of the timers have the same TimerFcn? Perhaps placing a pause(t) between the timer functions would help but that's a shot in the dark without knowing what those functions do.
Paul Murrin
Paul Murrin 2020-9-30
编辑：Paul Murrin 2020-9-30
The TimerFcn is a method of the GUI class. It mostly sets properties of GUI objects such as static text, lamp colours etc, based on the values of various properties.
The callback method is defined as:
function statusTimerFcn(app,~,~)
And this is passed to the timer setup as:
app.statusTimer = timer(...
'TimerFcn', @app.statusTimerFcn);
There is no direct recursion as far as I'm aware. Also the different timers have different callbacks.
Adam Danz
Adam Danz 2020-9-30
Can you identify which function is causing the error?
Please share the entire error message including the caller stack if available.
Paul Murrin
Paul Murrin 2020-9-30
That is the entire error message. I can't trap it so can't obtain a call stack.
I've managed to eliminate it in this instance by adding a startDelay which is longer than the app startup interval. It is a complex GUI app so takes several seconds to initialise. I guess the object is not fully ready when the timer first fires.
I've been grappling with the same error in various forms for a while and I am usually able to mitigate it but never get at the root cause and don't really understand what is going wrong.
Adam Danz
Adam Danz 2020-9-30
Usually errors that occur within AppDesigner indicate where the error is happening and this is an important bit of info. I had a feeling the timer fcn doing something too early within the initialization of the app. Sounds like you solved it with the start delay.

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