That's the way references work - what you're passing to your 'pass1' function is a pointer to the hash '$hashref' points to, not a copy of it, so local changes get applied to that global copy. If you want to pass a local copy, specify that: 
pass1({ params => {%$hashref} });  # {%$hashref} makes a (shallow) cop
+y of the hash '$hashref' 
                                   # points to and creates a new ref t
+o it.

[download]
If you do that, then you get: 
before pass1: 1
Inside pass1...
2
3
after pass1: 1

[download]
which is what I think you expect.

Added (shallow) note, AnomalousMonk is correct in his reply below!


Mike

In reply to Re: How to preserve values outside a sub by RMGir
in thread How to preserve values outside a sub by Anonymous Monk

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