ref: 2fe3b28f86ed4aa291fb8a620b948abe9c6a1f84
dir: /sys/src/cmd/python/Doc/lib/emailgenerator.tex/
\declaremodule{standard}{email.generator} \modulesynopsis{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 \refmodule{smtplib} module or the \refmodule{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 \refmodule{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{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 \module{email.generator} module: \begin{classdesc}{Generator}{outfp\optional{, mangle_from_\optional{, maxheaderlen}}} The constructor for the \class{Generator} class takes a file-like object called \var{outfp} for an argument. \var{outfp} must support the \method{write()} method and be usable as the output file in a Python extended print statement. Optional \var{mangle_from_} is a flag that, when \code{True}, puts a \samp{>} character in front of any line in the body that starts exactly as \samp{From }, i.e. \code{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 \ulink{WHY THE CONTENT-LENGTH FORMAT IS BAD} {http://www.jwz.org/doc/content-length.html} for details). \var{mangle_from_} defaults to \code{True}, but you might want to set this to \code{False} if you are not writing \UNIX{} mailbox format files. Optional \var{maxheaderlen} specifies the longest length for a non-continued header. When a header line is longer than \var{maxheaderlen} (in characters, with tabs expanded to 8 spaces), the header will be split as defined in the \module{email.header.Header} class. Set to zero to disable header wrapping. The default is 78, as recommended (but not required) by \rfc{2822}. \end{classdesc} The other public \class{Generator} methods are: \begin{methoddesc}[Generator]{flatten}{msg\optional{, unixfrom}} Print the textual representation of the message object structure rooted at \var{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 \var{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 \code{False} to inhibit the printing of the envelope delimiter. Note that for subparts, no envelope header is ever printed. \versionadded{2.2.2} \end{methoddesc} \begin{methoddesc}[Generator]{clone}{fp} Return an independent clone of this \class{Generator} instance with the exact same options. \versionadded{2.2.2} \end{methoddesc} \begin{methoddesc}[Generator]{write}{s} Write the string \var{s} to the underlying file object, i.e. \var{outfp} passed to \class{Generator}'s constructor. This provides just enough file-like API for \class{Generator} instances to be used in extended print statements. \end{methoddesc} As a convenience, see the methods \method{Message.as_string()} and \code{str(aMessage)}, a.k.a. \method{Message.__str__()}, which simplify the generation of a formatted string representation of a message object. For more detail, see \refmodule{email.message}. The \module{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. \begin{classdesc}{DecodedGenerator}{outfp\optional{, mangle_from_\optional{, maxheaderlen\optional{, fmt}}}} 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 \var{_mangle_from_} and \var{maxheaderlen} are as with the \class{Generator} base class. If the subpart is not of main type \mimetype{text}, optional \var{fmt} is a format string that is used instead of the message payload. \var{fmt} is expanded with the following keywords, \samp{\%(keyword)s} format: \begin{itemize} \item \code{type} -- Full MIME type of the non-\mimetype{text} part \item \code{maintype} -- Main MIME type of the non-\mimetype{text} part \item \code{subtype} -- Sub-MIME type of the non-\mimetype{text} part \item \code{filename} -- Filename of the non-\mimetype{text} part \item \code{description} -- Description associated with the non-\mimetype{text} part \item \code{encoding} -- Content transfer encoding of the non-\mimetype{text} part \end{itemize} The default value for \var{fmt} is \code{None}, meaning \begin{verbatim} [Non-text (%(type)s) part of message omitted, filename %(filename)s] \end{verbatim} \versionadded{2.2.2} \end{classdesc} \versionchanged[The previously deprecated method \method{__call__()} was removed]{2.5}