in reply to Re: A general method of locally overriding subroutines
in thread A general method of locally overriding subroutines

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->();
}

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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

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Re^3: A general method of locally overriding subroutines
by BrowserUk (Patriarch) on Mar 11, 2006 at 06:36 UTC

    Simpler, or did I miss something? 

    #! perl -slw
use strict;

$, = ' ';

sub a{ 'a' }
sub b{ 'b' }
sub c{ 'c' }

sub d{ ( a, b, c ) };

sub localize {
    no strict 'refs'; no warnings 'redefine';
    A: local *{ +shift } = sub{ 'changed' };
    goto A if @_ > 1;
    +shift->();
}

print d;
print localize qw[a b c], \&d;
print d;
print localize qw[a c], \&d;
print d;
__END__
C:\test>junk
a b c
changed changed changed
a b c
changed b changed
a b c

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Re^3: A general method of locally overriding subroutines
by dragonchild (Archbishop) on Mar 11, 2006 at 13:20 UTC
    Even so, it's easier to understand than the nested-subroutines solution.

    More importantly, the stackdump is more easily understood.

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

    I would hope there's something better than that. For one thing, my version doesn't allow each function to be a closure. Though, that's easy enough to fix, I suppose. 

    sub localize {
    my $real = pop;

    no strict 'refs'; no warnings 'redefine';
    goto CALL unless @_;
    AGAIN: my $v = shift;
    local *{$v} = do {
        my $v2 = $v;
        sub { "changed $v2" }
    };
    goto AGAIN if @_;
    CALL: $real->();
}

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    My criteria for good software:
    1. Does it work?
    2. Can someone else come in, make a change, and be reasonably certain no bugs were introduced?
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