Ruby

/*

* An Encoding instance represents a character encoding usable in Ruby. It is

* defined as a constant under the Encoding namespace. It has a name and

* optionaly, aliases:

*

* Encoding::ISO_8859_1.name

* #=> #<Encoding:ISO-8859-1>

*

* Encoding::ISO_8859_1.names

* #=> ["ISO-8859-1", "ISO8859-1"]

*

* Ruby methods dealing with encodings return or take Encoding instances as

* arguments (when a method accepts an Encoding instance as an argument, it can

* be passed an Encoding name or alias instead).

*

* "some string".encoding

* #=> #<Encoding:UTF-8>

*

* string = "some string".encode(Encoding::ISO_8859_1)

* #=> "some string"

* string.encoding

* #=> #<Encoding:ISO-8859-1>

*

* "some string".encode("ISO-8859-1")

* #=> "some string"

*

* <code>Encoding::ASCII_8BIT</code> is a special encoding that does not

* correspond to any character encoding. In fact it represents the absence of

* encoding and objects with this encoding can be seen as binary data.

*

* == Changing an encoding

*

* The associated Encoding of a String can can be changed in two different ways.

*

* First, it is possible to set the Encoding of a string to a new Encoding

* without changing the internal byte representation of the string, with the

* String#force_encoding method. This is how you can tell Ruby that another

* encoding is better suited to treat the string.

*

* string

* #=> "R\xC3\xA9sum\xC3\xA9"

* string.encoding

* #=> #<Encoding:ISO-8859-1>

* string.force_encoding(Encoding:UTF-8)

* #=> "Résumé"

*

* Second, it is possible to transcode a string, i.e. translate its internal

* byte representation to another encoding. Its associated encoding is also

* set to the other encoding. See String#encode for the various forms of

* transcoding, and the Encoding::Converter class for additional control over

* the transcoding process.

*

* string = "some string"

* #=> "some string"

* string.encoding

* #=> #<Encoding:UTF-8>

* string.encode!(Encoding::ISO_8859_1)

* #=> "some string"

* string.encoding

* #=> #<Encoding:ISO-8859-1>

*

* == Locale encoding

*

* All Ruby source code has an associated Encoding which any String literal

* created in the source code will be associated to.

*

* The default locale encoding is <code>Encoding::US-ASCII</code>, but it can

* be changed by a magic comment on the first line of the source code file (or

* second line, if there is a shebang line on the first). The comment must

* contain the word <code>coding</code> or <code>encoding</code>, followed

* by a colon, space and the Encoding name or alias:

*

* # encoding: UTF-8

*

* "some string".encoding

* #=> #<Encoding:UTF-8>

*

* The <code>__ENCODING__</code> keyword returns the locale encoding that is

* currently active:

*

* # encoding: ISO-8859-1

*

* __ENCODING__

* #=> #<Encoding:ISO-8859-1>

*

* == External encoding

*

* Each IO object has an external encoding which indicates the encoding that

* Ruby will use to read its data. By default Ruby sets the external

* encoding of an IO object to the default external encoding (initialized from

* the user's environment, set with the interpreter <code>-E</code> option or

* the Encoding.default_external= method). Encoding.default_external returns

* the current value of the external encoding.

*

* # Encoding.default_external

* #=> #<Encoding:UTF-8>

*

* $ ruby -E ISO-8859-1 -e "p Encoding.default_external"

* #<Encoding:ISO-8859-1>

*

* # Encoding.default_external = Encoding:ISO-8859-1

* #=> #<Encoding:ISO-8859-1>

* # Encoding.default_external

* #=> #<Encoding:ISO-8859-1>

*

* When you know that the actual encoding of the data of an IO object is not

* the default external encoding, you can reset its external encoding with

* IO#set_encoding or set it at IO object creation (see IO.new options).

*

* == Internal encoding

*

* To process the data of an IO object which has an encoding different

* from its external encoding, you can set its internal encoding. Ruby will use

* this internal encoding to transcode the data when it is read from the IO

* object.

*

* Conversely when data is written to the IO object, it is transcoded from the

* internal encoding to the external encoding of the IO object.

*

* The internal encoding of an IO object can be set with

* IO#set_encoding or at IO object creation (see IO.new options).

*

* The internal encoding is optional and when not set, the Ruby default

* internal encoding is used. If not explicitly set this default internal

* encoding is +nil+ meaning that by default, no transcoding occurs.

*

* The default internal encoding can be set with the interpreter option

* <code>-E</code> or Encoding.default_internal=. Encoding.default_internal

* returns the current value of the internal encoding.

*

* $ ruby -E ISO-8859-1:UTF-8 -e "p [Encoding.default_external, \

Encoding.default_internal]"

* [#<Encoding:ISO-8859-1>, #<Encoding:UTF-8>]

*

* # Encoding.default_internal

* #=> nil

* # Encoding.default_internal = Encoding::UTF_8

* #=> #<Encoding:UTF-8>

* # Encoding.default_internal

* #=> #<Encoding:UTF-8>

*

*/