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in reply to Re^3: Smartmatch alternatives
in thread Smartmatch alternatives

I see that it was added after 1.32 (most recent version installed here) ... 

1.33 -- Sun Oct 13 01:35 UTC 2013

  * Added any, all, none, notall list reduction functions
    (inspired by List::MoreUtils)

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Re^5: Smartmatch alternatives
by Laurent_R (Canon) on Dec 17, 2013 at 18:52 UTC
    If you don't have any, it is easy to implement it using the reduce function of List::Utils with something like this: 
    sub any {
    my $code_ref = shift;
    reduce { $a or $code_ref->(local $_ = $b) } @_;
}

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    Or, better: 
    sub any(&@) {
    my $code_ref = shift;
    reduce { $a or $code_ref->(local $_ = $b) } @_;
}

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    which makes it possible to call it with a syntax similar to grep: 
    <strike>print "true\n" if any { $_> 11 } qw /3 12 4 5 7/; # prints tru
+e

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     Update: the above line need to be this: 
    print "true\n" if any { $_> 11 } 0, qw /3 12 4 5 7/; # prints true

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      your any is always true!

        DB<12> use List::Util qw/reduce/

  DB<13> sub any(&@) {
               my $code_ref = shift;
               reduce { $a or $code_ref->(local $_ = $b) } @_;
           }

  DB<15> print "true\n" if any { $_ < 0 } qw /3 12 4 5 7/;
true

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      Cheers Rolf

      ( addicted to the Perl Programming Language)

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        Oops, you are absolutely right. I must have changed something at the last moment, and don't remember exactly what. It was working OK, but not anymore. I am too tired now to figure out what happened, it will have to be tomorrow. I tested it with various arrays, it was working perfectly alright. But it's no longer the case.
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        OK, to work correctly, the first element of the array passed to any needs to be false. There are two ways of doing it, I tested both ways, but then I made the mistake of removing both ways from my post. It can be done either as in the update I made in my post above (prepending a 0 to the list passed to any) or by changing the any function as follows: 

        sub any (&@) {
    my $code_ref = shift;
    unshift @_, 0;
    reduce { $a or $code_ref->(local $_ = $b) } @_;
}

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        Thank you Rolf for your remark.

        Update: It could also be done this way, perhaps the best one: 

        sub any (&@) {
    my $code_ref = shift;
    reduce { $a or $code_ref->(local $_ = $b) } 0, @_;
}

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Re^5: Smartmatch alternatives
by davido (Cardinal) on Dec 17, 2013 at 16:19 UTC

    Another good reason to run a recent Perl, I guess. ;) lol.

    Funny, I thought it went back farther than that.


    Dave

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      The most recent stable release of Perl only comes with List::Util 1.27.

      use Moops; class Cow :rw { has name => (default => 'Ermintrude') }; say Cow->new->name
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        Well, since I'm running Perl 5.18.2, I guess the fact that I have List::Util::any must mean that somewhere along the way I've installed the latest dual-lived version of the module.

        Anyway, is there any disagreement that "any" (under whichever banner it marches) is a reasonable utility for determining if any of the elements in an array meets some criteria? If I recall, it's also a PBP recommendation for the same reason I gave: That, unlike grep, it gives an appropriate and clear name to the functionality at work.


        Dave

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