mirror of
https://github.com/python/cpython.git
synced 2024-12-11 18:53:56 +08:00
113 lines
5.2 KiB
ReStructuredText
113 lines
5.2 KiB
ReStructuredText
:mod:`email`: Generating MIME documents
|
|
---------------------------------------
|
|
|
|
.. module:: email.generator
|
|
:synopsis: Generate flat text email messages from a message structure.
|
|
|
|
|
|
One of the most common tasks is to generate the flat text of the email message
|
|
represented by a message object structure. You will need to do this if you want
|
|
to send your message via the :mod:`smtplib` module or the :mod:`nntplib` module,
|
|
or print the message on the console. Taking a message object structure and
|
|
producing a flat text document is the job of the :class:`Generator` class.
|
|
|
|
Again, as with the :mod:`email.parser` module, you aren't limited to the
|
|
functionality of the bundled generator; you could write one from scratch
|
|
yourself. However the bundled generator knows how to generate most email in a
|
|
standards-compliant way, should handle MIME and non-MIME email messages just
|
|
fine, and is designed so that the transformation from flat text, to a message
|
|
structure via the :class:`~email.parser.Parser` class, and back to flat text,
|
|
is idempotent (the input is identical to the output).
|
|
|
|
Here are the public methods of the :class:`Generator` class, imported from the
|
|
:mod:`email.generator` module:
|
|
|
|
|
|
.. class:: Generator(outfp, mangle_from_=True, maxheaderlen=78)
|
|
|
|
The constructor for the :class:`Generator` class takes a file-like object called
|
|
*outfp* for an argument. *outfp* must support the :meth:`write` method and be
|
|
usable as the output file for the :func:`print` function.
|
|
|
|
Optional *mangle_from_* is a flag that, when ``True``, puts a ``>`` character in
|
|
front of any line in the body that starts exactly as ``From``, i.e. ``From``
|
|
followed by a space at the beginning of the line. This is the only guaranteed
|
|
portable way to avoid having such lines be mistaken for a Unix mailbox format
|
|
envelope header separator (see `WHY THE CONTENT-LENGTH FORMAT IS BAD
|
|
<http://www.jwz.org/doc/content-length.html>`_ for details). *mangle_from_*
|
|
defaults to ``True``, but you might want to set this to ``False`` if you are not
|
|
writing Unix mailbox format files.
|
|
|
|
Optional *maxheaderlen* specifies the longest length for a non-continued header.
|
|
When a header line is longer than *maxheaderlen* (in characters, with tabs
|
|
expanded to 8 spaces), the header will be split as defined in the
|
|
:class:`~email.header.Header` class. Set to zero to disable header wrapping.
|
|
The default is 78, as recommended (but not required) by :rfc:`2822`.
|
|
|
|
The other public :class:`Generator` methods are:
|
|
|
|
|
|
.. method:: flatten(msg, unixfrom=False)
|
|
|
|
Print the textual representation of the message object structure rooted at
|
|
*msg* to the output file specified when the :class:`Generator` instance
|
|
was created. Subparts are visited depth-first and the resulting text will
|
|
be properly MIME encoded.
|
|
|
|
Optional *unixfrom* is a flag that forces the printing of the envelope
|
|
header delimiter before the first :rfc:`2822` header of the root message
|
|
object. If the root object has no envelope header, a standard one is
|
|
crafted. By default, this is set to ``False`` to inhibit the printing of
|
|
the envelope delimiter.
|
|
|
|
Note that for subparts, no envelope header is ever printed.
|
|
|
|
.. method:: clone(fp)
|
|
|
|
Return an independent clone of this :class:`Generator` instance with the
|
|
exact same options.
|
|
|
|
.. method:: write(s)
|
|
|
|
Write the string *s* to the underlying file object, i.e. *outfp* passed to
|
|
:class:`Generator`'s constructor. This provides just enough file-like API
|
|
for :class:`Generator` instances to be used in the :func:`print` function.
|
|
|
|
As a convenience, see the methods :meth:`Message.as_string` and
|
|
``str(aMessage)``, a.k.a. :meth:`Message.__str__`, which simplify the generation
|
|
of a formatted string representation of a message object. For more detail, see
|
|
:mod:`email.message`.
|
|
|
|
The :mod:`email.generator` module also provides a derived class, called
|
|
:class:`DecodedGenerator` which is like the :class:`Generator` base class,
|
|
except that non-\ :mimetype:`text` parts are substituted with a format string
|
|
representing the part.
|
|
|
|
|
|
.. class:: DecodedGenerator(outfp[, mangle_from_=True, maxheaderlen=78, fmt=None)
|
|
|
|
This class, derived from :class:`Generator` walks through all the subparts of a
|
|
message. If the subpart is of main type :mimetype:`text`, then it prints the
|
|
decoded payload of the subpart. Optional *_mangle_from_* and *maxheaderlen* are
|
|
as with the :class:`Generator` base class.
|
|
|
|
If the subpart is not of main type :mimetype:`text`, optional *fmt* is a format
|
|
string that is used instead of the message payload. *fmt* is expanded with the
|
|
following keywords, ``%(keyword)s`` format:
|
|
|
|
* ``type`` -- Full MIME type of the non-\ :mimetype:`text` part
|
|
|
|
* ``maintype`` -- Main MIME type of the non-\ :mimetype:`text` part
|
|
|
|
* ``subtype`` -- Sub-MIME type of the non-\ :mimetype:`text` part
|
|
|
|
* ``filename`` -- Filename of the non-\ :mimetype:`text` part
|
|
|
|
* ``description`` -- Description associated with the non-\ :mimetype:`text` part
|
|
|
|
* ``encoding`` -- Content transfer encoding of the non-\ :mimetype:`text` part
|
|
|
|
The default value for *fmt* is ``None``, meaning ::
|
|
|
|
[Non-text (%(type)s) part of message omitted, filename %(filename)s]
|