Octave provides several ways of recovering from errors. There are
try/catch blocks,
unwind_protect/unwind_protect_cleanup blocks,
and finally the onCleanup command.
The onCleanup command associates an ordinary Octave variable (the
trigger) with an arbitrary function (the action). Whenever the Octave variable
ceases to exist—whether due to a function return, an error, or simply because
the variable has been removed with clear—then the assigned function
is executed.
The function can do anything necessary for cleanup such as closing open file handles, printing an error message, or restoring global variables to their initial values. The last example is a very convenient idiom for Octave code. For example:
function rand42
old_state = rand ("state");
restore_state = onCleanup (@() rand ("state", old_state));
rand ("state", 42);
...
endfunction # rand generator state restored by onCleanup
obj = onCleanup (function) ¶Create a special object that executes a given function upon destruction.
If the object is copied to multiple variables (or cell or struct array elements) or returned from a function, then function will be executed only after the last copy of the object is cleared.
The input function is a handle to a function. The handle may point to an
anonymous function in order to directly place commands in the onCleanup
call.
Programming Note: If multiple local onCleanup variables are created, the
order in which they are called is unspecified. For similar functionality
See The unwind_protect Statement.
Example
octave:1> trigger = onCleanup (@() disp ('onCleanup was executed'));
octave:2> clear trigger
onCleanup was executed
octave:3