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76 lines
3.6 KiB
TeX
76 lines
3.6 KiB
TeX
\declaremodule{standard}{email.Generator}
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\modulesynopsis{Generate flat text email messages from a message object tree.}
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One of the most common tasks is to generate the flat text of the email
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message represented by a message object tree. You will need to do
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this if you want to send your message via the \refmodule{smtplib}
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module or the \refmodule{nntplib} module, or print the message on the
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console. Taking a message object tree and producing a flat text
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document is the job of the \class{Generator} class.
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Again, as with the \refmodule{email.Parser} module, you aren't limited
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to the functionality of the bundled generator; you could write one
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from scratch yourself. However the bundled generator knows how to
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generate most email in a standards-compliant way, should handle MIME
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and non-MIME email messages just fine, and is designed so that the
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transformation from flat text, to an object tree via the
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\class{Parser} class,
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and back to flat text, be idempotent (the input is identical to the
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output).
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Here are the public methods of the \class{Generator} class:
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\begin{classdesc}{Generator}{outfp\optional{, mangle_from_\optional{,
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maxheaderlen}}}
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The constructor for the \class{Generator} class takes a file-like
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object called \var{outfp} for an argument. \var{outfp} must support
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the \method{write()} method and be usable as the output file in a
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Python 2.0 extended print statement.
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Optional \var{mangle_from_} is a flag that, when true, puts a ``>''
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character in front of any line in the body that starts exactly as
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\samp{From } (i.e. \code{From} followed by a space at the front of the
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line). This is the only guaranteed portable way to avoid having such
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lines be mistaken for \emph{Unix-From} headers (see
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\ulink{WHY THE CONTENT-LENGTH FORMAT IS BAD}
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{http://home.netscape.com/eng/mozilla/2.0/relnotes/demo/content-length.html}
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for details).
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Optional \var{maxheaderlen} specifies the longest length for a
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non-continued header. When a header line is longer than
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\var{maxheaderlen} (in characters, with tabs expanded to 8 spaces),
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the header will be broken on semicolons and continued as per
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\rfc{2822}. If no semicolon is found, then the header is left alone.
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Set to zero to disable wrapping headers. Default is 78, as
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recommended (but not required) by \rfc{2822}.
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\end{classdesc}
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The other public \class{Generator} methods are:
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\begin{methoddesc}[Generator]{__call__}{msg\optional{, unixfrom}}
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Print the textual representation of the message object tree rooted at
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\var{msg} to the output file specified when the \class{Generator}
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instance was created. Sub-objects are visited depth-first and the
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resulting text will be properly MIME encoded.
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Optional \var{unixfrom} is a flag that forces the printing of the
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\emph{Unix-From} (a.k.a. envelope header or \code{From_} header)
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delimiter before the first \rfc{2822} header of the root message
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object. If the root object has no \emph{Unix-From} header, a standard
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one is crafted. By default, this is set to 0 to inhibit the printing
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of the \emph{Unix-From} delimiter.
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Note that for sub-objects, no \emph{Unix-From} header is ever printed.
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\end{methoddesc}
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\begin{methoddesc}[Generator]{write}{s}
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Write the string \var{s} to the underlying file object,
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i.e. \var{outfp} passed to \class{Generator}'s constructor. This
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provides just enough file-like API for \class{Generator} instances to
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be used in extended print statements.
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\end{methoddesc}
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As a convenience, see the methods \method{Message.as_string()} and
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\code{str(aMessage)}, a.k.a. \method{Message.__str__()}, which
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simplify the generation of a formatted string representation of a
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message object. For more detail, see \refmodule{email.Message}.
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