In my use-case I could actually replace the variable's ref in the functions pad with a new one.

But in general tie %var is supposed to dock to an existing variable without changing it's name or reference!

That's why the pedant in me is surprised that I have to jump thru all those hoops.

And yes I tried to not reinvent the wheel and found Tie::Watch , what they do is actually a flat copy of the whole data-structure in the constructor.

-shadow (default 1) is 0 to disable array and hash shadowing. To prevent infinite recursion Tie::Watch maintains parallel variables for arrays and hashes. When the watchpoint is created the parallel shadow variable is initialized with the watched variable's contents, and when the watchpoint is deleted the shadow variable is copied to the original variable. Thus, changes made during the watch process are not lost. Shadowing is on my default. If you disable shadowing any changes made to an array or hash are lost when the watchpoint is deleted.