encode::encoder.3

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.\" ========================================================================
.\"
.IX Title "Encode::Encoder 3"
.TH Encode::Encoder 3 "2007-12-18" "perl v5.10.0" "Perl Programmers Reference Guide"
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
.\" way too many mistakes in technical documents.
.if n .ad l
.nh
.SH "NAME"
Encode::Encoder \-\- Object Oriented Encoder
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 10
\&  use Encode::Encoder;
\&  # Encode::encode("ISO\-8859\-1", $data); 
\&  Encode::Encoder\->new($data)\->iso_8859_1; # OOP way
\&  # shortcut
\&  use Encode::Encoder qw(encoder);
\&  encoder($data)\->iso_8859_1;
\&  # you can stack them!
\&  encoder($data)\->iso_8859_1\->base64;  # provided base64() is defined
\&  # you can use it as a decoder as well
\&  encoder($base64)\->bytes(\*(Aqbase64\*(Aq)\->latin1;
\&  # stringified
\&  print encoder($data)\->utf8\->latin1;  # prints the string in latin1
\&  # numified
\&  encoder("\ex{abcd}\ex{ef}g")\->utf8 == 6; # true. bytes::length($data)
.Ve
.SH "ABSTRACT"
.IX Header "ABSTRACT"
\&\fBEncode::Encoder\fR allows you to use Encode in an object-oriented
style.  This is not only more intuitive than a functional approach,
but also handier when you want to stack encodings.  Suppose you want
your \s-1UTF\-8\s0 string converted to Latin1 then Base64: you can simply say
.PP
.Vb 1
\&  my $base64 = encoder($utf8)\->latin1\->base64;
.Ve
.PP
instead of
.PP
.Vb 2
\&  my $latin1 = encode("latin1", $utf8);
\&  my $base64 = encode_base64($utf8);
.Ve
.PP
or the lazier and more convoluted
.PP
.Vb 1
\&  my $base64 = encode_base64(encode("latin1", $utf8));
.Ve
.SH "Description"
.IX Header "Description"
Here is how to use this module.
.IP "\(bu" 4
There are at least two instance variables stored in a hash reference,
{data} and {encoding}.
.IP "\(bu" 4
When there is no method, it takes the method name as the name of the
encoding and encodes the instance \fIdata\fR with \fIencoding\fR.  If successful,
the instance \fIencoding\fR is set accordingly.
.IP "\(bu" 4
You can retrieve the result via \->data but usually you don't have to 
because the stringify operator ("") is overridden to do exactly that.
.Sh "Predefined Methods"
.IX Subsection "Predefined Methods"
This module predefines the methods below:
.ie n .IP "$e\fR = Encode::Encoder\->new([$data, \f(CW$encoding]);" 4
.el .IP "\f(CW$e\fR = Encode::Encoder\->new([$data, \f(CW$encoding\fR]);" 4
.IX Item "$e = Encode::Encoder->new([$data, $encoding]);"
returns an encoder object.  Its data is initialized with \f(CW$data\fR if
present, and its encoding is set to \f(CW$encoding\fR if present.
.Sp
When \f(CW$encoding\fR is omitted, it defaults to utf8 if \f(CW$data\fR is already in
utf8 or "" (empty string) otherwise.
.IP "\fIencoder()\fR" 4
.IX Item "encoder()"
is an alias of Encode::Encoder\->\fInew()\fR.  This one is exported on demand.
.ie n .IP "$e\->data([$data])" 4
.el .IP "\f(CW$e\fR\->data([$data])" 4
.IX Item "$e->data([$data])"
When \f(CW$data\fR is present, sets the instance data to \f(CW$data\fR and returns the
object itself.  Otherwise, the current instance data is returned.
.ie n .IP "$e\->encoding([$encoding])" 4
.el .IP "\f(CW$e\fR\->encoding([$encoding])" 4
.IX Item "$e->encoding([$encoding])"
When \f(CW$encoding\fR is present, sets the instance encoding to \f(CW$encoding\fR and
returns the object itself.  Otherwise, the current instance encoding is
returned.
.ie n .IP "$e\->bytes([$encoding])" 4
.el .IP "\f(CW$e\fR\->bytes([$encoding])" 4
.IX Item "$e->bytes([$encoding])"
decodes instance data from \f(CW$encoding\fR, or the instance encoding if
omitted.  If the conversion is successful, the instance encoding
will be set to "".
.Sp
The name \fIbytes\fR was deliberately picked to avoid namespace tainting
\&\*(-- this module may be used as a base class so method names that appear
in Encode::Encoding are avoided.
.Sh "Example: base64 transcoder"
.IX Subsection "Example: base64 transcoder"
This module is designed to work with Encode::Encoding.
To make the Base64 transcoder example above really work, you could
write a module like this:
.PP
.Vb 10
\&  package Encode::Base64;
\&  use base \*(AqEncode::Encoding\*(Aq;
\&  _\|_PACKAGE_\|_\->Define(\*(Aqbase64\*(Aq);
\&  use MIME::Base64;
\&  sub encode{ 
\&      my ($obj, $data) = @_; 
\&      return encode_base64($data);
\&  }
\&  sub decode{
\&      my ($obj, $data) = @_; 
\&      return decode_base64($data);
\&  }
\&  1;
\&  _\|_END_\|_
.Ve
.PP
And your caller module would be something like this:
.PP
.Vb 2
\&  use Encode::Encoder;
\&  use Encode::Base64;
\&
\&  # now you can really do the following
\&
\&  encoder($data)\->iso_8859_1\->base64;
\&  encoder($base64)\->bytes(\*(Aqbase64\*(Aq)\->latin1;
.Ve
.Sh "Operator Overloading"
.IX Subsection "Operator Overloading"
This module overloads two operators, stringify ("") and numify (0+).
.PP
Stringify dumps the data inside the object.
.PP
Numify returns the number of bytes in the instance data.
.PP
They come in handy when you want to print or find the size of data.
.SH "SEE ALSO"
.IX Header "SEE ALSO"
Encode,
Encode::Encoding