Clever. It just needs one more goto to handle the empty case (no overrides) gracefully: 
sub localize {
    my $real = pop;
    no strict 'refs';
    goto CALL unless @_;
    AGAIN: local *{shift@_} = sub { 'changed' };
    goto AGAIN if @_;
    CALL: $real->();
}

[download]
Even so, it's easier to understand than the nested-subroutines solution.

I wonder if anybody out there has got something even simpler.

Tom Moertel : Blog / Talks / CPAN / LectroTest / PXSL / Coffee / Movie Rating Decoder

In reply to Re^2: A general method of locally overriding subroutines by tmoertel
in thread A general method of locally overriding subroutines by tmoertel

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