Re: Avoid warnings while formatting with repeated format lines

Hello hexcoder,

I don’t know much about Perl’s format command, but a search found Re^2: Use of uninitialized value in formline? which seems to have the answer:

use strict;
use warnings;
use open ':locale';

sub print_data
{
    my ($name, @f);

    format START =
.===================.
|@<<<<<<|           |
$name
|       |           |
.=======.===========.
|@<<<<<<|  @<</@>>  |~~
shift(@f) || '', shift(@f) || '', shift(@f) || ''
.=======.===========.
.

    binmode STDOUT, ':raw:crlf';
    my $ofh = select(STDOUT);
    $~      = "START";
    $name   = 'TAB';
    @f      = ('Step2', 0, 4, 'Step3', 4, 4);
    write;
}

print_data;
[download]

Output:

 0:01 >perl 2079_SoPW.pl
.===================.
|TAB    |           |
|       |           |
.=======.===========.
|Step2  |     /  4  |
|Step3  |  4  /  4  |
.=======.===========.

 0:01 >
[download]

Looks like a limitation of the format function: it wants to see a separate argument for each placeholder, and it doesn’t like undef.

Anyway, hope that helps,

Athanasius <°(((>< contra mundum Iustus alius egestas vitae, eros Piratica,

Comment on Re: Avoid warnings while formatting with repeated format lines Select or Download Code

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Re^2: Avoid warnings while formatting with repeated format lines
by Anonymous Monk on Aug 24, 2022 at 14:50 UTC

If the Perl in question is at least 5.10, your solution could use shift(@f) // '', shift(@f) // '', shift(@f) // '' to duplicate the original output.

[reply]
[d/l]

Re^3: Avoid warnings while formatting with repeated format lines

by Athanasius (Archbishop) on Aug 24, 2022 at 15:34 UTC

Of course, you’re right, // is correct here; || will replace 0 with the empty string, which is not what is wanted.

Good catch!

Athanasius <°(((>< contra mundum Iustus alius egestas vitae, eros Piratica,

[reply]
[d/l]
[select]

Re^2: Avoid warnings while formatting with repeated format lines
by hexcoder (Curate) on Aug 24, 2022 at 14:54 UTC

Athanasius

[reply]


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