in reply to 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;

Output:

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

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,

Replies are listed 'Best First'.
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.

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

    I did some super search before posting, but obviously I missed this one. This special handling should be added to the official documentation, I think!

    Greetings, hexcoder