MIME::WordDecoder(3)

📦
version 5.517 · 14 versions
, in fedora 44

💖 MIME::WordDecoder — the tea ☕

okay so bestie, welcome to MIME::WordDecoder, a User Contributed Perl Documentation page (section 3, library-calls girlie 💅). This is the module that takes those cursed =?ISO-8859-1?Q?...?= blobs and turns them into something a human can actually read. Buckle up 🎀

✨ NAME ✨

MIME::WordDecoder — decode RFC 2047 encoded words to a local representation.

🚨 WARNING: Most of this module is deprecated and may disappear. The only function you should use for MIME decoding is mime_to_perl_string.

🌸 SYNOPSIS 🌸

Go peep MIME::Words for the basics of encoded words, and scroll to DESCRIPTION for how this class actually works, iykyk.

use MIME::WordDecoder;

### Get the default word-decoder (used by unmime()):
$wd = default MIME::WordDecoder;

### Get a word-decoder which maps to ISO-8859-1 (Latin1):
$wd = supported MIME::WordDecoder "ISO-8859-1";

### Decode a MIME string (e.g., into Latin1) via the default decoder:
$str = $wd->decode('To: =?ISO-8859-1?Q?Keld_J=F8rn_Simonsen?= <keld>');

### Decode a string using the default decoder, non-OO style:
$str = unmime('To: =?ISO-8859-1?Q?Keld_J=F8rn_Simonsen?= <keld>');

### Decode a string to an internal Perl string, non-OO style
### The result is likely to have the UTF8 flag ON.
$str = mime_to_perl_string('To: =?ISO-8859-1?Q?Keld_J=F8rn_Simonsen?= <keld>');

🦋 DESCRIPTION 🦋

🚨 WARNING: Most of this module is deprecated and may disappear. It duplicates (badly) the function of the standard 'Encode' module. The only function you should rely on is mime_to_perl_string.

So like. A MIME::WordDecoder is, at its core, a hash 💅. That hash maps a character set name (US-ASCII, ISO-8859-1, etc.) to a subroutine that knows how to take bytes in that charset and turn them into the target string representation. Ideally that target would be Unicode, but we're not gonna overspecify the translation happening here — if you wanna convert MIME strings straight to Big5, that's your own decision bestie, live your truth 🫶.

The subroutine gets called with two arguments: DATA (the data in the given character set) and CHARSET (the upcased character set name).

For example, a lil guy that keeps 7-bit chars as-is and turns 8-bit chars into '#':

### Keep 7-bit characters as-is, convert 8-bit characters to '#':
sub keep7bit {
    local $_ = shift;
    tr/\x00-\x7F/#/c;
    $_;
}

And here's a decoder that uses it:

### Construct a decoder:
$wd = MIME::WordDecoder->new({'US-ASCII'   => "KEEP",   ### sub { $_[0] }
                              'ISO-8859-1' => \&keep7bit,
                              'ISO-8859-2' => \&keep7bit,
                              'Big5'       => "WARN",
                              '*'          => "DIE"});

### Convert some MIME text to a pure ASCII string...
$ascii = $wd->decode('To: =?ISO-8859-1?Q?Keld_J=F8rn_Simonsen?= <keld>');

### ...which will now hold: "To: Keld J#rn Simonsen <keld>"

The UTF-8 built-in decoder decodes everything into Perl's internal string format, possibly turning on the internal UTF8 flag. Use it like this:

$wd = supported MIME::WordDecoder 'UTF-8';
$perl_string = $wd->decode('To: =?ISO-8859-1?Q?Keld_J=F8rn_Simonsen?= <keld>');
# perl_string will be a valid UTF-8 string with the "UTF8" flag set.

Generally, you should use the UTF-8 decoder in preference to unmime. periodt ✨

👑 PUBLIC INTERFACE 👑

default [DECODER]

Class method. Get/set the default DECODER object.

supported CHARSET, [DECODER]

Class method. If you just hand it CHARSET, it returns a decoder object that maps data into that character set (and it forces the character set to be ALL-UPPERCASE, no cap).

$wd = supported MIME::WordDecoder "ISO-8859-1";

If you pass DECODER, it installs that object instead:

MIME::WordDecoder->supported("ISO-8859-1" =>
                             (new MIME::WordDecoder::ISO_8859 "1"));
🙈 You should not override this method.

new [\@HANDLERS]

Class method, a.k.a. the constructor. If you pass \@HANDLERS, then @HANDLERS gets passed to handler() to initialize the internal map.

handler CHARSET=>\&SUBREF, ...

Instance method. Sets the handler SUBREF for a given CHARSET — as many pairs as you feel like supplying, go off 💅.

When translating a MIME-encoded string, a given SUBREF gets invoked when translating a block of text in character set CHARSET. The subroutine is invoked with these arguments:

  • DATA — the data in the given character set.
  • CHARSET — the upcased character set name, which may prove useful if you're using the same SUBREF for multiple CHARSETs.
  • DECODER — the decoder itself, if it contains configuration information that your handler function needs.

For example:

$wd = new MIME::WordDecoder;
$wd->handler('US-ASCII'   => "KEEP");
$wd->handler('ISO-8859-1' => \&handle_latin1,
             'ISO-8859-2' => \&handle_latin1,
             '*'          => "DIE");

Notice that, much like with %SIG, the SUBREF can also be pulled from a set of special keywords:

  • KEEP — pass data through unchanged.
  • IGNORE — ignore data in this character set, without warning.
  • WARN — ignore data in this character set, with warning.
  • DIE — fatal exception with can't handle character set message.

The subroutine for the special CHARSET of 'raw' is used for raw (non-MIME-encoded) text, which is supposed to be US-ASCII. The handler for 'raw' defaults to whatever was specified for 'US-ASCII' at the time of construction.

The subroutine for the special CHARSET of '*' is used for any unrecognized character set. The default action for '*' is WARN.

decode STRING

Instance method. Decode a STRING which might contain MIME-encoded components into a local representation (e.g., UTF-8, etc.).

unmime STRING

Function, exported. Decodes the given STRING using the default() decoder. See default().

You should consider using the UTF-8 decoder instead — it decodes MIME strings into Perl's internal string format. 👑

mime_to_perl_string

Function, exported. Decodes the given STRING into an internal Perl Unicode string. You should use this function in preference to all others, fr fr.

The result of mime_to_perl_string is likely to have Perl's UTF8 flag set.

🧚 SUBCLASSES 🧚

MIME::WordDecoder::ISO_8859

A simple decoder that keeps US-ASCII and the 7-bit characters of ISO-8859 character sets and UTF8, and also keeps 8-bit characters from the indicated character set. iconic behavior honestly 🌈

### Construct:
$wd = new MIME::WordDecoder::ISO_8859 2;    ### ISO-8859-2

### What to translate unknown characters to (can also use empty):
### Default is "?".
$wd->unknown("?");

### Collapse runs of unknown characters to a single unknown()?
### Default is false.
$wd->collapse(1);

According to http://czyborra.com/charsets/iso8859.html (ca. November 2000):

ISO 8859 is a full series of 10 (and soon even more) standardized multilingual single-byte coded (8bit) graphic character sets for writing in alphabetic languages:

  1. Latin1 (West European)
  2. Latin2 (East European)
  3. Latin3 (South European)
  4. Latin4 (North European)
  5. Cyrillic
  6. Arabic
  7. Greek
  8. Hebrew
  9. Latin5 (Turkish)
  10. Latin6 (Nordic)

The ISO 8859 charsets are not even remotely as complete as the truly great Unicode but they have been around and usable for quite a while (first registered Internet charsets for use with MIME) and have already offered a major improvement over the plain 7bit US-ASCII.

Characters 0 to 127 are always identical with US-ASCII and the positions 128 to 159 hold some less used control characters: the so-called C1 set from ISO 6429.

MIME::WordDecoder::US_ASCII

A subclass of the ISO-8859-1 decoder which discards 8-bit characters. You're probably better off using ISO-8859-1, ngl.

🌟 SEE ALSO 🌟

  • MIME::Tools

💜 AUTHOR 💜

and that's the whole page bestie 🎀 this was pulled from perl v5.42.0, dated 2026-02-11 — go decode some cursed headers and slay 💅✨

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