--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/symbian-qemu-0.9.1-12/python-2.6.1/Doc/library/email.charset.rst Fri Jul 31 15:01:17 2009 +0100
@@ -0,0 +1,253 @@
+:mod:`email`: Representing character sets
+-----------------------------------------
+
+.. module:: email.charset
+ :synopsis: Character Sets
+
+
+This module provides a class :class:`Charset` for representing character sets
+and character set conversions in email messages, as well as a character set
+registry and several convenience methods for manipulating this registry.
+Instances of :class:`Charset` are used in several other modules within the
+:mod:`email` package.
+
+Import this class from the :mod:`email.charset` module.
+
+.. versionadded:: 2.2.2
+
+
+.. class:: Charset([input_charset])
+
+ Map character sets to their email properties.
+
+ This class provides information about the requirements imposed on email for a
+ specific character set. It also provides convenience routines for converting
+ between character sets, given the availability of the applicable codecs. Given
+ a character set, it will do its best to provide information on how to use that
+ character set in an email message in an RFC-compliant way.
+
+ Certain character sets must be encoded with quoted-printable or base64 when used
+ in email headers or bodies. Certain character sets must be converted outright,
+ and are not allowed in email.
+
+ Optional *input_charset* is as described below; it is always coerced to lower
+ case. After being alias normalized it is also used as a lookup into the
+ registry of character sets to find out the header encoding, body encoding, and
+ output conversion codec to be used for the character set. For example, if
+ *input_charset* is ``iso-8859-1``, then headers and bodies will be encoded using
+ quoted-printable and no output conversion codec is necessary. If
+ *input_charset* is ``euc-jp``, then headers will be encoded with base64, bodies
+ will not be encoded, but output text will be converted from the ``euc-jp``
+ character set to the ``iso-2022-jp`` character set.
+
+ :class:`Charset` instances have the following data attributes:
+
+
+ .. attribute:: input_charset
+
+ The initial character set specified. Common aliases are converted to
+ their *official* email names (e.g. ``latin_1`` is converted to
+ ``iso-8859-1``). Defaults to 7-bit ``us-ascii``.
+
+
+ .. attribute:: header_encoding
+
+ If the character set must be encoded before it can be used in an email
+ header, this attribute will be set to ``Charset.QP`` (for
+ quoted-printable), ``Charset.BASE64`` (for base64 encoding), or
+ ``Charset.SHORTEST`` for the shortest of QP or BASE64 encoding. Otherwise,
+ it will be ``None``.
+
+
+ .. attribute:: body_encoding
+
+ Same as *header_encoding*, but describes the encoding for the mail
+ message's body, which indeed may be different than the header encoding.
+ ``Charset.SHORTEST`` is not allowed for *body_encoding*.
+
+
+ .. attribute:: output_charset
+
+ Some character sets must be converted before they can be used in email headers
+ or bodies. If the *input_charset* is one of them, this attribute will
+ contain the name of the character set output will be converted to. Otherwise, it will
+ be ``None``.
+
+
+ .. attribute:: input_codec
+
+ The name of the Python codec used to convert the *input_charset* to
+ Unicode. If no conversion codec is necessary, this attribute will be
+ ``None``.
+
+
+ .. attribute:: output_codec
+
+ The name of the Python codec used to convert Unicode to the
+ *output_charset*. If no conversion codec is necessary, this attribute
+ will have the same value as the *input_codec*.
+
+ :class:`Charset` instances also have the following methods:
+
+
+ .. method:: get_body_encoding()
+
+ Return the content transfer encoding used for body encoding.
+
+ This is either the string ``quoted-printable`` or ``base64`` depending on
+ the encoding used, or it is a function, in which case you should call the
+ function with a single argument, the Message object being encoded. The
+ function should then set the :mailheader:`Content-Transfer-Encoding`
+ header itself to whatever is appropriate.
+
+ Returns the string ``quoted-printable`` if *body_encoding* is ``QP``,
+ returns the string ``base64`` if *body_encoding* is ``BASE64``, and
+ returns the string ``7bit`` otherwise.
+
+
+ .. method:: convert(s)
+
+ Convert the string *s* from the *input_codec* to the *output_codec*.
+
+
+ .. method:: to_splittable(s)
+
+ Convert a possibly multibyte string to a safely splittable format. *s* is
+ the string to split.
+
+ Uses the *input_codec* to try and convert the string to Unicode, so it can
+ be safely split on character boundaries (even for multibyte characters).
+
+ Returns the string as-is if it isn't known how to convert *s* to Unicode
+ with the *input_charset*.
+
+ Characters that could not be converted to Unicode will be replaced with
+ the Unicode replacement character ``'U+FFFD'``.
+
+
+ .. method:: from_splittable(ustr[, to_output])
+
+ Convert a splittable string back into an encoded string. *ustr* is a
+ Unicode string to "unsplit".
+
+ This method uses the proper codec to try and convert the string from
+ Unicode back into an encoded format. Return the string as-is if it is not
+ Unicode, or if it could not be converted from Unicode.
+
+ Characters that could not be converted from Unicode will be replaced with
+ an appropriate character (usually ``'?'``).
+
+ If *to_output* is ``True`` (the default), uses *output_codec* to convert
+ to an encoded format. If *to_output* is ``False``, it uses *input_codec*.
+
+
+ .. method:: get_output_charset()
+
+ Return the output character set.
+
+ This is the *output_charset* attribute if that is not ``None``, otherwise
+ it is *input_charset*.
+
+
+ .. method:: encoded_header_len()
+
+ Return the length of the encoded header string, properly calculating for
+ quoted-printable or base64 encoding.
+
+
+ .. method:: header_encode(s[, convert])
+
+ Header-encode the string *s*.
+
+ If *convert* is ``True``, the string will be converted from the input
+ charset to the output charset automatically. This is not useful for
+ multibyte character sets, which have line length issues (multibyte
+ characters must be split on a character, not a byte boundary); use the
+ higher-level :class:`Header` class to deal with these issues (see
+ :mod:`email.header`). *convert* defaults to ``False``.
+
+ The type of encoding (base64 or quoted-printable) will be based on the
+ *header_encoding* attribute.
+
+
+ .. method:: body_encode(s[, convert])
+
+ Body-encode the string *s*.
+
+ If *convert* is ``True`` (the default), the string will be converted from
+ the input charset to output charset automatically. Unlike
+ :meth:`header_encode`, there are no issues with byte boundaries and
+ multibyte charsets in email bodies, so this is usually pretty safe.
+
+ The type of encoding (base64 or quoted-printable) will be based on the
+ *body_encoding* attribute.
+
+ The :class:`Charset` class also provides a number of methods to support
+ standard operations and built-in functions.
+
+
+ .. method:: __str__()
+
+ Returns *input_charset* as a string coerced to lower
+ case. :meth:`__repr__` is an alias for :meth:`__str__`.
+
+
+ .. method:: __eq__(other)
+
+ This method allows you to compare two :class:`Charset` instances for
+ equality.
+
+
+ .. method:: __ne__(other)
+
+ This method allows you to compare two :class:`Charset` instances for
+ inequality.
+
+The :mod:`email.charset` module also provides the following functions for adding
+new entries to the global character set, alias, and codec registries:
+
+
+.. function:: add_charset(charset[, header_enc[, body_enc[, output_charset]]])
+
+ Add character properties to the global registry.
+
+ *charset* is the input character set, and must be the canonical name of a
+ character set.
+
+ Optional *header_enc* and *body_enc* is either ``Charset.QP`` for
+ quoted-printable, ``Charset.BASE64`` for base64 encoding,
+ ``Charset.SHORTEST`` for the shortest of quoted-printable or base64 encoding,
+ or ``None`` for no encoding. ``SHORTEST`` is only valid for
+ *header_enc*. The default is ``None`` for no encoding.
+
+ Optional *output_charset* is the character set that the output should be in.
+ Conversions will proceed from input charset, to Unicode, to the output charset
+ when the method :meth:`Charset.convert` is called. The default is to output in
+ the same character set as the input.
+
+ Both *input_charset* and *output_charset* must have Unicode codec entries in the
+ module's character set-to-codec mapping; use :func:`add_codec` to add codecs the
+ module does not know about. See the :mod:`codecs` module's documentation for
+ more information.
+
+ The global character set registry is kept in the module global dictionary
+ ``CHARSETS``.
+
+
+.. function:: add_alias(alias, canonical)
+
+ Add a character set alias. *alias* is the alias name, e.g. ``latin-1``.
+ *canonical* is the character set's canonical name, e.g. ``iso-8859-1``.
+
+ The global charset alias registry is kept in the module global dictionary
+ ``ALIASES``.
+
+
+.. function:: add_codec(charset, codecname)
+
+ Add a codec that map characters in the given character set to and from Unicode.
+
+ *charset* is the canonical name of a character set. *codecname* is the name of a
+ Python codec, as appropriate for the second argument to the :func:`unicode`
+ built-in, or to the :meth:`encode` method of a Unicode string.
+