and it don't even run under strict, what I'm missing here ?

You are missing that the ~~ tells to repeat shifting @f1 even after it is empty. Trying to build yet another line after the third, shift @f1 returns an undefined value, which then - alas, cannot be dereferenced.

One solution:

my $foo = [('') x 9];
format =
+-----------------------+
| @ @ @ | @ @ @ | @ @ @ |~~ 
@{ shift @f1 || $foo }
|-------+-------+-------|
| @ @ @ | @ @ @ | @ @ @ |~~ 
@{ shift @f2 || $foo } 
|-------+-------+-------|
| @ @ @ | @ @ @ | @ @ @ |~~ 
@{ shift @f3 || $foo } 
+-----------------------+
.
write;

[download]

You could also push the array reference filled with empty elements ($foo) onto @f1, @f2 and @f3.

my $foo = [('') x 9];
push @$_, $foo for \@f1,\@f2,\@f3;
format =
+-----------------------+
| @ @ @ | @ @ @ | @ @ @ |~~
@{shift @f1}
|-------+-------+-------|
| @ @ @ | @ @ @ | @ @ @ |~~
@{shift @f2}
|-------+-------+-------|
| @ @ @ | @ @ @ | @ @ @ |~~
@{shift @f3}
+-----------------------+
.
write;

[download]

In reply to Re: format issues by shmem
in thread format issues by Fox

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.