1Mail::DKIM::TextWrap(3)User Contributed Perl DocumentatioMnail::DKIM::TextWrap(3)
2
6 Mail::DKIM::TextWrap - text wrapping module written for use with DKIM
7
9 use Mail::DKIM::TextWrap;
10 Just add the above line to any program that uses Mail::DKIM::Signer and
12 your signatures will automatically be wrapped to 72 characters.
13
15 my $output = "";
16 my $tw = Mail::DKIM::TextWrap->new(
17 Margin => 10,
18 Output => \$output,
19 );
20 $tw->add("Mary had a little lamb, whose fleece was white as snow.\n");
21 $tw->finish;
22 print $output;
24
26 This is a general-purpose text-wrapping module that I wrote because I
27 had some specific needs with Mail::DKIM that none of the contemporary
28 text-wrapping modules offered.
29 Specifically, it offers the ability to change wrapping options in the
31 middle of a paragraph. For instance, with a DKIM signature:
32 DKIM-Signature: a=rsa; c=simple; h=first:second:third:fourth;
34 b=Xr2mo2wmb1LZBwmEJElIPezal7wQQkRQ8WZtxpofkNmXTjXf8y2f0
35 the line-breaks can be inserted next to any of the colons of the h=
37 tag, or any character of the b= tag. The way I implemented this was to
38 serialize the signature one element at a time, changing the text-
39 wrapping options at the start and end of each tag.
40
42 Text wrapping options can be specified when calling new(), or by simply
43 changing the property as needed. For example, to change the number of
44 characters allowed per line:
45 $tw->{Margin} = 20;
47 Break
49 a regular expression matching characters where a line break can be
50 inserted. Line breaks are inserted AFTER a matching substring. The
51 default is "/\s/".
52 BreakBefore
54 a regular expression matching characters where a line break can be
55 inserted. Line breaks are inserted BEFORE a matching substring.
56 Usually, you want to use Break, rather than BreakBefore. The
57 default is "undef".
58 Margin
60 specifies how many characters to allow per line. The default is
61 72. If no place to line-break is found on a line, the line will
62 extend beyond this margin.
63 Separator
65 the text to insert when a linebreak is needed. The default is
66 "\n". If you want to set a following-line indent (e.g. all lines
67 but the first begin with four spaces), use something like "\n ".
68 Swallow
70 a regular expression matching characters that can be omitted when a
71 line break occurs. For example, if you insert a line break between
72 two words, then you are replacing a "space" with the line break, so
73 you are omitting the space. On the other hand, if you insert a line
74 break between two parts of a hyphenated word, then you are breaking
75 at the hyphen, but you still want to display the hyphen. The
76 default is "/\s/".
77
79 new() - create a new text-wrapping object
80 my $tw = Mail::DKIM::TextWrap->new(
81 Output => \$output,
82 %wrapping_options,
83 );
84 The text-wrapping object encapsulates the current options and the
86 current state of the text stream. In addition to specifying text
87 wrapping options as described in the section above, the following
88 options are recognized:
89 Output
91 a scalar reference, or a glob reference, to specify where the
92 "wrapped" text gets output to. If not specified, the default of
93 STDOUT is used.
94
96 add() - process some text that can be wrapped
97 $tw->add("Mary had a little lamb.\n");
98 You can add() all the text at once, or add() the text in parts by
100 calling add() multiple times.
101 finish() - call when no more text is to be added
103 $tw->finish;
104 Call this when finished adding text, so that any remaining text in
106 TextWrap's buffers will be output.
107 flush() - output the current partial word, if any
109 $tw->flush;
110 Call this whenever changing TextWrap's parameters in the middle of a
112 string of words. It explicitly allows a line-break at the current
113 position in the string, regardless of whether it matches the current
114 break pattern.
115perl v5.28.1 2018-10-13 Mail::DKIM::TextWrap(3)