#18600: add policy to add_string, and as_bytes and __bytes__ methods.
This was triggered by wanting to make the doctest in email.policy.rst pass;
as_bytes and __bytes__ are clearly useful now that we have BytesGenerator.
Also updated the Message docs to document the policy keyword that was
added in 3.3.
diff --git a/Doc/library/email.message.rst b/Doc/library/email.message.rst
index 2c7be8b..7a74220 100644
--- a/Doc/library/email.message.rst
+++ b/Doc/library/email.message.rst
@@ -31,19 +31,32 @@
Here are the methods of the :class:`Message` class:
-.. class:: Message()
+.. class:: Message(policy=compat32)
- The constructor takes no arguments.
+ The *policy* argument determiens the :mod:`~email.policy` that will be used
+ to update the message model. The default value, :class:`compat32
+ <email.policy.Compat32>` maintains backward compatibility with the
+ Python 3.2 version of the email package. For more information see the
+ :mod:`~email.policy` documentation.
+
+ .. versionchanged:: 3.3 The *policy* keyword argument was added.
- .. method:: as_string(unixfrom=False, maxheaderlen=0)
+ .. method:: as_string(unixfrom=False, maxheaderlen=0, policy=None)
Return the entire message flattened as a string. When optional *unixfrom*
- is ``True``, the envelope header is included in the returned string.
- *unixfrom* defaults to ``False``. Flattening the message may trigger
- changes to the :class:`Message` if defaults need to be filled in to
- complete the transformation to a string (for example, MIME boundaries may
- be generated or modified).
+ is true, the envelope header is included in the returned string.
+ *unixfrom* defaults to ``False``. For backward compabitility reasons,
+ *maxheaderlen* defaults to ``0``, so if you want a different value you
+ must override it explicitly (the value specified for *max_line_length* in
+ the policy will be ignored by this method). The *policy* argument may be
+ used to override the default policy obtained from the message instance.
+ This can be used to control some of the formatting produced by the
+ method, since the specified *policy* will be passed to the ``Generator``.
+
+ Flattening the message may trigger changes to the :class:`Message` if
+ defaults need to be filled in to complete the transformation to a string
+ (for example, MIME boundaries may be generated or modified).
Note that this method is provided as a convenience and may not always
format the message the way you want. For example, by default it does
@@ -59,10 +72,57 @@
g.flatten(msg)
text = fp.getvalue()
+ If the message object contains binary data that is not encoded according
+ to RFC standards, the non-compliant data will be replaced by unicode
+ "unknown character" code points. (See also :meth:`.as_bytes` and
+ :class:`~email.generator.BytesGenerator`.)
+
+ .. versionchanged:: 3.4 the *policy* keyword argument was added.
+
.. method:: __str__()
- Equivalent to ``as_string(unixfrom=True)``.
+ Equivalent to :meth:`.as_string()`. Allows ``str(msg)`` to produce a
+ string containing the formatted message.
+
+
+ .. method:: as_bytes(unixfrom=False, policy=None)
+
+ Return the entire message flattened as a bytes object. When optional
+ *unixfrom* is true, the envelope header is included in the returned
+ string. *unixfrom* defaults to ``False``. The *policy* argument may be
+ used to override the default policy obtained from the message instance.
+ This can be used to control some of the formatting produced by the
+ method, since the specified *policy* will be passed to the
+ ``BytesGenerator``.
+
+ Flattening the message may trigger changes to the :class:`Message` if
+ defaults need to be filled in to complete the transformation to a string
+ (for example, MIME boundaries may be generated or modified).
+
+ Note that this method is provided as a convenience and may not always
+ format the message the way you want. For example, by default it does
+ not do the mangling of lines that begin with ``From`` that is
+ required by the unix mbox format. For more flexibility, instantiate a
+ :class:`~email.generator.BytesGenerator` instance and use its
+ :meth:`flatten` method directly. For example::
+
+ from io import BytesIO
+ from email.generator import BytesGenerator
+ fp = BytesIO()
+ g = BytesGenerator(fp, mangle_from_=True, maxheaderlen=60)
+ g.flatten(msg)
+ text = fp.getvalue()
+
+ .. versionadded:: 3.4
+
+
+ .. method:: __bytes__()
+
+ Equivalent to :meth:`.as_bytes()`. Allows ``bytes(msg)`` to produce a
+ bytes object containing the formatted message.
+
+ .. versionadded:: 3.4
.. method:: is_multipart()
diff --git a/Doc/library/email.policy.rst b/Doc/library/email.policy.rst
index 54ebb1c..93c5350 100644
--- a/Doc/library/email.policy.rst
+++ b/Doc/library/email.policy.rst
@@ -105,7 +105,8 @@
>>> import os
>>> with open('converted.txt', 'wb') as f:
- ... f.write(msg.as_string(policy=msg.policy.clone(linesep=os.linesep)))
+ ... f.write(msg.as_bytes(policy=msg.policy.clone(linesep=os.linesep)))
+ 17
Policy objects can also be combined using the addition operator, producing a
policy object whose settings are a combination of the non-default values of the
diff --git a/Doc/whatsnew/3.4.rst b/Doc/whatsnew/3.4.rst
index 80b4b01..6011f8e 100644
--- a/Doc/whatsnew/3.4.rst
+++ b/Doc/whatsnew/3.4.rst
@@ -195,6 +195,26 @@
plain tuple. (Contributed by Claudiu Popa in :issue:`17818`.)
+email
+-----
+
+:meth:`~email.message.Message.as_string` now accepts a *policy* argument to
+override the default policy of the message when generating a string
+representation of it. This means that ``as_string`` can now be used in more
+circumstances, instead of having to create and use a :mod:`~email.generator` in
+order to pass formatting parameters to its ``flatten`` method.
+
+New method :meth:`~email.message.Message.as_bytes` added to produce a bytes
+representation of the message in a fashion similar to how ``as_string``
+produces a string representation. It does not accept the *maxheaderlen*
+argument, but does accept the *unixfrom* and *policy* arguments. The
+:class:`~email.message.Message` :meth:`~email.message.Message.__bytes__` method
+calls it, meaning that ``bytes(mymsg)`` will now produce the intuitive
+result: a bytes object containing the fully formatted message.
+
+(Contributed by R. David Murray in :issue:`18600`.)
+
+
functools
---------