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You are right be worried, your example code is just a bit to complex to make it evident at first glance.

There is no logical reason why nested calls of the same function (i.e. recursions) should act differently to nested calls of different functions.

see updated code, especially the second paragraph contrasting the bug.

Cheers Rolf

UPDATE:

to be sure to avoid any side effects from eval within the debugger here a standalone file for testing:

use warnings; use strict; use 5.10.0; my $x; sub delchar { $x =~ s/(\w)// ? $1 . delchar() . $1 : "x" } $x='abc'; say delchar(); # => "cccxccc" sub del1 { $x =~ s/(\w)// ? $1 . del2() . $1 : "x" } sub del2 { $x =~ s/(\w)// ? $1 . del3() . $1 : "x" } sub del3 { $x =~ s/(\w)// ? $1 . del4() . $1 : "x" } sub del4 { $x =~ s/(\w)// ? $1 . del5() . $1 : "x" } $x='abc'; say del1(); # => "abcxcba"

UPDATE:

Best practice is to copy captures like $1 ASAP! (not only in recursions)

DB<105> sub delchar { my $m; $m = $1 if $x =~ s/(\w)//; $m ? $m . +delchar() . $m : "-" } => 0 DB<106> $x='abc'; delchar() => "abc-cba" DB<107> sub delchar { local $m; $m = $1 if $x =~ s/(\w)//; $m ? $m + . delchar() . $m : "-" } => 0 DB<108> $x='abc'; delchar() => "abc-cba"

In reply to Re^3: 'Dynamic scoping' of capture variables ($1, $2, etc.) by LanX
in thread 'Dynamic scoping' of capture variables ($1, $2, etc.) by AnomalousMonk

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