Matlab onCleanup function not executed -

i ran following issue in matlab r2013a, reason not understand not call oncleanup function when in function timer (including timerfcn) defined.

i add 2 minimal examples showing problem:

first working version cleanup routine called expected:

function mytest(time)   t = timer();   myclean = oncleanup(@() disp('function ended'));   pause(time); end 

and buggy version in cleanup not called (neither when function ends or when ctrl+c pressed)

function mytest2(time)   t = timer();   t.timerfcn = @(o,s)disp(' ... waiting time');    myclean = oncleanup(@() disp('function ends'));   pause(time); end 

i not find hints in documentation why timer or more specific definition of timerfcn change execution of cleanup code?

ouch - nasty. it's not bug, it's not you'd expect documentation, , it's not you'd want. fortunately it's pretty easy work around.

firstly, what's happening?

well, oncleanup returns oncleanup object. object sole purpose have destructor method set @() disp('function ends'). when object goes out of scope (which expect @ end of function mytest2), gets deleted, destructor method executes, , message gets displayed. that's expect, think.

but when create anonymous function @(o,s)disp(' ... waiting time'), , assign timerfcn of timer, takes copy of entire current workspace of function mytest2, including oncleanup object. timer created in base workspace (not function workspace), , remains in existence @ end of function, along oncleanup object, never goes out of scope, never gets deleted, destructor function never runs, , don't message.

note that:

1. if run a = timerfindall; delete(a); in base workspace, message, you've explicitly deleted timer along oncleanup object.
2. this behaviour anonymous functions taking copy of entire workspace documented, although may not aware of it, , although don't want work here. it's nasty.

fortunately, it's easy work around:

function mytest3(time)   t = timer();   settimerfcn(t)   myclean = oncleanup(@() disp('function ends'));   pause(time); end  function settimerfcn(t)   t.timerfcn = @(o,s)disp(' ... waiting time');  end 

now, when anonymous function created takes copy of local workspace (i.e. subfunction settimerfcn), not include oncleanup object. oncleanup object goes out of scope @ point expect to, , everything's fine.

hope helps!