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Re^2: Correct idiom for default parameters

by mrider (Sexton)
on Apr 28, 2010 at 17:41 UTC ( #837358=note: print w/ replies, xml ) Need Help??


in reply to Re: Correct idiom for default parameters
in thread Correct idiom for default parameters

Ack! 5.8.8 here (sigh).

Thanks for the suggestion though.


Comment on Re^2: Correct idiom for default parameters
Re^3: Correct idiom for default parameters
by BrowserUk (Pope) on Apr 28, 2010 at 19:00 UTC

    This is 5.8 accessible and might even be more palatable?

    Updated per LanX's correction below.

    sub test{ my( $p1, $p2, $p3) = map{ scalar @_ ? shift : $_ }( 1, 2, 3 ); print "p1:$p1; p2:$p2; p3:$p3"; };; test();; p1:1; p2:2; p3:3 test( 'a' );; p1:a; p2:2; p3:3 test( 'a', 'b', 'c' );; p1:a; p2:b; p3:c

    Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
    "Science is about questioning the status quo. Questioning authority".
    In the absence of evidence, opinion is indistinguishable from prejudice.
      careful!

      passing undef in between will break your idiom.

      IMHO better check scalar @_ or care explicitly about passing undef !

      sub defaults { my( $p1, $p2, $p3) = map{ defined $_[0] ? shift : $_ }( 1, 2, 3 ); + print "p1:$p1; p2:$p2; p3:$p3\n"; }; defaults(undef, 0, 0);

      Cheers Rolf

        Sorry, I don't follow?

        Passing undef gives exactly the effect I would expect and desire. That of accepting the default for that parameter:

        test( 'a', undef, 'c' );; p1:a; p2:2; p3:c

        Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
        "Science is about questioning the status quo. Questioning authority".
        In the absence of evidence, opinion is indistinguishable from prejudice.

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