jcwren has asked for the wisdom of the Perl Monks concerning the following question:

I am off on a jobsite without my trusty Perl CD Bookshelf.

I need(want) to pass named parameters to a subroutine, ala CGI..

do_this_cool_function (-retire=>'early', -payscale=>-55.00, -pizza=>'cold', -beer=>none);

I'm using 'use strict' and '-w'. The compiler throws up on my shoes with
"Can't use string ("-spot") as a HASH ref while "strict refs" in use at t.pl line 13."

A) What do I need to do remove this error,
B) How do I access the named arguments in the subroutine?.

Replies are listed 'Best First'.
Re: Passing named parameters
by snowcrash (Friar) on May 02, 2000 at 10:45 UTC
    Access your argument in the subroutine like this: 
    #!/usr/bin/perl -w 

use strict;

sub do_this_cool_function {
  my %args = (
        -retire     => "never",
        -pizza     => "cheese",
        -payscale   => 0,
        -beer      => "guiness",
        @_,         # argument pair list goes here
    );

    print "I wanna retire $args{-retire} if my pizza is $args{-pizza}.
+\n";
}

do_this_cool_function(-retire=>'early', -payscale=>-55.00, -pizza=>'co
+ld', -beer=>'none');

    [download]
    i don't get your error by the way. the only error your function call gives, is the following, because you didn't quote 'none': 
    Bareword "none" not allowed while "strict subs" in use at ./test.pl li
+ne 17.
Unquoted string "none" may clash with future reserved word at ./test.p
+l line 17.
Execution of ./test.pl aborted due to compilation errors.

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RE: Passing named parameters
by ChOas (Curate) on May 02, 2000 at 10:50 UTC
    Hi!

    Eeehm you might want to put ' thingies around your
    keys aswel that hash, that might help

    and for B:
    I'd think this'd work:
    sub do_this_cool_function(@)
    {
    my %Param=@_;
    # Now address your params like this:
    my $When=$Param{'-retire'};
    my $Wages=$Param('-payscale'};
    my $Favourite_temperature=$Param{'-pizza'};

    }
    That's how I'd do it.
[reply]
      No, this is proper syntax: do_this_cool_function (-retire=>'early', -payscale=>-55.00, -pizza=>'cold', -beer=>none); This should work fine as in many modules like CGI.pm. The leading '-' in -retire will perl to interpret '-retire' as a string. Here is a snip from perlop 
             Unary "-" performs arithmetic negation if the operand is
       numeric.  If the operand is an identifier, a string
       consisting of a minus sign concatenated with the
       identifier is returned.  Otherwise, if the string starts
       with a plus or minus, a string starting with the opposite
       sign is returned.  One effect of these rules is that
       -bareword is equivalent to "-bareword".

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        Which is why -beer isn't a bareword. But the => is equivalent to a , (comma) thus ending the bareword, er string. So then
            -beer, none
        will result in none being a bareword. At least, that's how I understand it.
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