Perl5中“write”和“format”的替代品是什么?

格式的主要问题是对全局变量的依赖。有关格式的其他问题,请参见 Perl Best Practices

现代的解决方案是 Perl6::Form

下面是格式代码到 Perl6::窗体 . 我不知道 很好,所以可能有一些方法可以使它更好或更真实地与原来的例子:

#!/usr/bin/perl

use strict;
use warnings;

use Perl6::Form;

while(<DATA>) {
    my ($aprille, $lorem) = split(/\|/, $_, 2);
    print form(
        "{>} {[[[[[[[[[[[[[[[[[[[[[[[[} | {[[[[[[[[[[[[[[[[[[}",
        $.,  $aprille,                  $lorem,
        "                               |                     ",
    );
}

__DATA__
WHAN that Aprille with his shoures soote       |Lorem ipsum dolor sit amet,
The droghte of Marche hath perced to the roote,|consectetur adipisicing elit,
And bathed every veyne in swich licour,        |sed do eiusmod tempor
Of which vertu engendred is the flour;         |incididunt ut labore et dolore
Whan Zephirus eek with his swete breeth        |magna aliqua. Ut enim ad minim
Inspired hath in every holt and heeth          |veniam, quis nostrud
The tendre croppes, and the yonge sonne        |exercitation exercitation
Hath in the Ram his halfe cours y-ronne,       |ullamco laboris nisi ut ali-
And smale fowles maken melodye,                |quip ex ea commodo conse-
That slepen al the night with open ye,         |quat. Duis aute irure dolor
So priketh hem nature in hir corages:          |in reprehenderit in volup-
Than longen folk to goon on pilgrimages,       |tate velit esse cillium dol-
And palmers for to seken straunge strondes,    |ore eu fugiat nulla pariatur.
To ferne halwes, couthe in sondry londes;      |Lorem ipsum dolor sit amet,
And specially, from every shires ende          |consectetur adipisicing elit,
Of Engelond, to Caunterbury they wende,        |sed do eiusmod tempor
The holy blisful martir for to seke,           |incididunt ut labore et dolore
That hem hath holpen, whan that they were seke.|magna aliqua. Ut enim ad minim
And now for something completely different. Nice plumage.|Norwegian blue.

perl5加在perl4之上的主要内容 format write 是 formline $^A ,数字格式和包作用域,但这些主要是不必要的绒毛。当前的格式化指令集只比perl4s大一点:

@    start of regular field
^    start of special field
<    pad character for left justification
|    pad character for centering
>    pad character for right justification
#    pad character for a right justified numeric field
0    instead of first #: pad number with leading zeroes
.    decimal point within a numeric field
...  terminate a text field, show "..." as truncation evidence
@*   variable width field for a multi-line value
^*   variable width field for next line of a multi-line value
~    suppress line with all fields empty
~~   repeat line until all fields are exhausted

其他鲜为人知的增强功能包括支持LC_NUMERIC local,能够使用 {} \r

我仍然使用 格式 时不时的。这是我几周前写的一个程序的一部分。

sub init_screen() {
    our %Opt;
    my  $cols;

    if ($Opt{width}) {
         $cols  = $Opt{width};
    } 
    elsif (am_unixy()) {
        ($cols) = `stty size 2>&1` =~ /^\d+ (\d+)$/;
    }
    else {
         # FALLTHROUGH to ||= init on next line
    }

    $cols ||= 80; # non-unix or stty error
    $cols  -=  2;

    my $format  = "format STDOUT = \n"
                . '    ^'    . '<' x ($cols-4) . "\n"
                . '$_' . "\n"
                . "       ^" . "<" x ($cols-6) . "~~\n"
                . '$_' . "\n"
                . ".\n"
                . "1;" # for true eval return
                ;

    eval($format) || die;
}

根据当前屏幕宽度动态调整可能更漂亮,但仍然有用。