in reply to Re^2: formline, undefined format STDOUT
in thread formline, undefined format STDOUT

As documented in perlform, ~~ should be used for changing values that finally become undefined. 
#!/usr/bin/perl
use warnings;
use strict;

my @l = ('This is long string', 'Another long one');
my @s = ('s', 'S');

format =
~~ @<<<<<<<<<<<<<<<<<<< @<
shift @l, shift @s
.
write;

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It's time you read the documentation again. I've never used formats in Perl, and I hope I never will; but I was able to put this together in one minute.

لսႽ† ᥲᥒ⚪⟊Ⴙᘓᖇ Ꮅᘓᖇ⎱ Ⴙᥲ𝇋ƙᘓᖇ

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Re^4: formline, undefined format STDOUT
by Anonymous Monk on Apr 20, 2015 at 17:23 UTC

    Thnx for your help, this is what I was looking for : 

    #!/usr/bin/perl
use warnings;
use strict;

my @row;
my @f_map = ('f1', 'f2');
my $f = "format = \n"
        . ('^' . '<' x 15 . '|') x scalar(@f_map) . "\n"
        . '@row' . "\n"
        . ('^' . '<' x 15 . '|') x scalar(@f_map) . "~~\n"
        . '@row' . "\n"
        . ".\n";
eval($f);

# 
@row = ('blah1' x 10, 'blah2' x 10);
write;

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    output : 

    blah1blah1blah1b|blah2blah2blah2b|
lah1blah1blah1bl|lah2blah2blah2bl|
ah1blah1blah1bla|ah2blah2blah2bla|
h1              |h2              |

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