`mlock`

Locks the running function in memory so that clear does not reset it.

Syntax

mlock

Called inside a function file, locks that function.

Description

Persistent variables normally disappear when the function is cleared with clear or clear all. A locked function stays in memory, so its persistent variables survive until munlock is called or the session ends. mlock is valid only inside a function file; call it once, usually at the start.

Use it for state that must outlast a clear, such as a call counter or a cache.

Example

State that survives clear

writelines(["function r = counter()", "  mlock;", "  persistent n", "  if isempty(n), n = 0; end", "  n = n + 1; r = n;", "end"], 'counter.m');
counter;
counter;
clear counter
counter

Output

ans = 3

Notes

In MatLivre mlock records the lock, so mislocked reports true, but clear never resets the persistent variables of any function, locked or not.

mlock