Perl Cookbook

Reformatting Paragraphs

Problem

Your string is too big to fit the screen, and you want to break it up into lines of words, without splitting a word between lines. For instance, a style correction script might read a text file a paragraph at a time, replacing bad phrases with good ones. Replacing a phrase like utilizes the inherent functionality of with uses will change the length of lines, so it must somehow reformat the paragraphs when they’re output.

Solution

Use the standard Text::Wrap module to put line breaks at the right place.

use Text::Wrap;
@OUTPUT = wrap($LEADTAB, $NEXTTAB, @PARA);

Discussion

The Text::Wrap module provides the wrap function, shown in Example 1.3, which takes a list of lines and reformats them into a paragraph having no line more than $Text::Wrap::columns characters long. We set $columns to 20, ensuring that no line will be longer than 20 characters. We pass wrap two arguments before the list of lines: the first is the indent for the first line of output, the second the indent for every subsequent line.

Example 1-3. wrapdemo

#!/usr/bin/perl -w
# wrapdemo - show how Text::Wrap works

@input = ("Folding and splicing is the work of an editor,",
          "not a mere collection of silicon",
          "and",
          "mobile electrons!");

use Text::Wrap qw($columns &wrap);

$columns = 20;
print "0123456789" x 2, "\n";
print wrap("    ", "  ", @input), "\n";

The result of this program is:

               
                  01234567890123456789
               
                      Folding and
               
                    splicing is the
               
                    work of an
               
                    editor, not a
               
                    mere collection
               
                   of silicon and ...