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Diffstat (limited to 'Doc/library/email.policy.rst')
| -rw-r--r-- | Doc/library/email.policy.rst | 25 |
1 files changed, 25 insertions, 0 deletions
diff --git a/Doc/library/email.policy.rst b/Doc/library/email.policy.rst index 9ab949e..31b13c1 100644 --- a/Doc/library/email.policy.rst +++ b/Doc/library/email.policy.rst @@ -196,6 +196,25 @@ added matters. To illustrate:: custom ``Message`` objects) should also provide such an attribute, otherwise defects in parsed messages will raise unexpected errors. + .. method:: header_max_count(name) + + Return the maximum allowed number of headers named *name*. + + Called when a header is added to a :class:`~email.message.Message` + object. If the returned value is not ``0`` or ``None``, and there are + already a number of headers with the name *name* equal to the value + returned, a :exc:`ValueError` is raised. + + Because the default behavior of ``Message.__setitem__`` is to append the + value to the list of headers, it is easy to create duplicate headers + without realizing it. This method allows certain headers to be limited + in the number of instances of that header that may be added to a + ``Message`` programmatically. (The limit is not observed by the parser, + which will faithfully produce as many headers as exist in the message + being parsed.) + + The default implementation returns ``None`` for all header names. + .. method:: header_source_parse(sourcelines) The email package calls this method with a list of strings, each string @@ -366,6 +385,12 @@ added matters. To illustrate:: The class provides the following concrete implementations of the abstract methods of :class:`Policy`: + .. method:: header_max_count(name) + + Returns the value of the + :attr:`~email.headerregistry.BaseHeader.max_count` attribute of the + specialized class used to represent the header with the given name. + .. method:: header_source_parse(sourcelines) The implementation of this method is the same as that for the |