in reply to Using formats for 2-columnprinting

Untested except by running it in the version of Perl installed in my head: 
{
  my $value;
  my $hash_ref;
  my $done;
  sub get_key {
    unless ($done) {
      (my $key, $value) = each %$hash_ref or # yes, $value is out of s
+cope
        $done = 1;
    }
    defined $key ? $key : "";
  }
  sub get_value {
    defined $value ? $value : "";
  }
  sub set_hash {
    $hash_ref = shift;
    keys %$hash_ref; # reset each()
    $done = 0;
  }
}

set_hash(\%hash_you_want_to_scan);
write STDOUT;

format STDOUT =
@>>>>> @###     @>>>>> @### ~~
get_key(), get_value(), get_key(), get_value()
.

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Note the use of the repeating format line to execute that value as long as data is available, then stop when it's not.

-- Randal L. Schwartz, Perl hacker

update: Change that middle subroutine to: 
  sub get_key {
    my $key;
    unless ($done) {
      ($key, $value) = each %$hash_ref or # yes, $value is out of scop
+e
        $done = 1;
    }
    defined $key ? $key : "";
  }

[download]
Too early in the morning for this. {grin}
update 2: Yes, those @#### need to be changed to @<<<< as well. Thanks for actually running the code, jcwren!

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(jcwren) Re: (2) Using formats for 2-columnprinting
by jcwren (Prior) on Oct 03, 2000 at 18:14 UTC
    I tried what you wrote, just for grins. I had to change the get_key() routine slightly to make it pass 'use strict' and -w. I get a whole bunch of errors of 'Argument "" isn't numeric in formline at t.pl line 42'.

    Update #1: I, too, have modified this code to reflect merlyn's change. However, I still get the same error message...

    Update #2: It was determined that using the original format code wasn't working because the @### doesn't work with ~~, since you can't get an empty string. Changing these to <'s fixed it.

    But, I don't know jack about formats, so I can't fix it. Any thoughts? And what version of Perl are you running in your head? 5.005_03, or 5.6? <G> 
    #!/usr/local/bin/perl -w

use strict;

my %hash_you_want_to_scan = ('kudra'      => 1, 
                             'neshura'    => 2, 
                             'Ozymandias' => 3,
                             'merlyn'     => 4,
                            );
                            
{
  my $value;
  my $hash_ref;
  my $done;
  
  sub get_key {
    my $key;

    unless ($done) {
      ($key, $value) = each %$hash_ref or # yes, $value is out of scop
+e
        $done = 1;
    }
    defined $key ? $key : "";
  }
  
  sub get_value {
    defined $value ? $value : "";
  }
  
  sub set_hash {
    $hash_ref = shift;
    keys %$hash_ref; # reset each()
    $done = 0;
  }
}

set_hash(\%hash_you_want_to_scan);
write STDOUT;

format STDOUT =
@<<<<< @<<<     @<<<<< @<<< ~~
get_key(), get_value(), get_key(), get_value()
.

    [download]
    Original code that merlyn identified as broke was: 
      sub get_key {
    my $key;
    unless ($done) {
      ($key, my $value) = each %$hash_ref or # yes, $value is out of s
+cope
        $done = 1;
    }
    defined $key ? $key : "";
  }

    [download]
    (It's the extra 'my' in front of the $value, which was wrecking the scope).
    Original format that caused the runaway format error: 
    format STDOUT =
@>>>>> @###     @>>>>> @### ~~
get_key(), get_value(), get_key(), get_value()
.

    [download]


    --Chris

    e-mail jcwren
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      You broke it. Leave it the way I wrote it, and try again. The $key is getting my'ed in that line. The $value is going into the next outer scope. I even said that in the comment!

      -- Randal L. Schwartz, Perl hacker

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