Matlab fails to provide a meaningsful error message in this situation. It's left to the user to provide a work-around.
Here is a small example of my work-around. It is code from the on-line help with a bit of error handling added together with code that causes an error: buf = 1; disp( buf(2) ). The trick is: try, overflowHandler_(eventSrc,eventData), catch me, disp(getReport(me)), end
Run
sec = setupSEC;
sec.prop1 = 5;
sec.prop1 = 15;
returns to the command window
The value of Prop1 is overflowing!
It's value was: 5
It's current value is: 15
Attempted to access buf(2); index out of bounds because numel(buf)=1.
Error in overflowHandler>overflowHandler_ (line 13)
disp( buf(2) )
Error in overflowHandler (line 3)
overflowHandler_( eventSrc, eventData )
Error in SimpleEventClass/set.prop1 (line 14)
notify( this,'Overflow',SpecialEventDataClass( org_value ) );
where
function sec = setupSEC
% Create an object and attach the listener
sec = SimpleEventClass;
addlistener( sec, 'Overflow', @overflowHandler )
end
and
classdef SimpleEventClass < handle
properties
prop1 = 0;
end
events
Overflow
end
methods
function set.prop1( this, value )
org_value = this.prop1;
this.prop1 = value;
if ( this.prop1 > 10)
% Trigger the event using custom event data
notify( this, 'Overflow', SpecialEventDataClass( org_value ) );
end
end
end
end
and
classdef SpecialEventDataClass < event.EventData
properties
OrgValue = 0;
end
methods
function eventData = SpecialEventDataClass( value )
eventData.OrgValue = value;
end
end
end
and
function overflowHandler( eventSrc, eventData )
try
overflowHandler_( eventSrc, eventData )
catch me
disp( getReport( me ) )
end
end
function overflowHandler_( eventSrc, eventData )
disp('The value of Prop1 is overflowing!')
disp(['It''s value was: ' num2str( eventData.OrgValue )])
disp(['It''s current value is: ' num2str( eventSrc.prop1 )])
buf = 1;
disp( buf(2) )
end
I use the same approach with code invoked by a timer. I've found it really helpful. See Debug code invoked by timer
