Doc/lib/emailencoders.tex

   1 \declaremodule{standard}{email.Encoders}
   2 \modulesynopsis{Encoders for email message payloads.}
   3
   4 When creating \class{Message} objects from scratch, you often need to
   5 encode the payloads for transport through compliant mail servers.
   6 This is especially true for \mimetype{image/*} and \mimetype{text/*}
   7 type messages containing binary data.
   8
   9 The \module{email} package provides some convenient encodings in its
  10 \module{Encoders} module.  These encoders are actually used by the
  11 \class{MIMEImage} and \class{MIMEText} class constructors to provide default
  12 encodings.  All encoder functions take exactly one argument, the
  13 message object to encode.  They usually extract the payload, encode
  14 it, and reset the payload to this newly encoded value.  They should also
  15 set the \mailheader{Content-Transfer-Encoding} header as appropriate.
  16
  17 Here are the encoding functions provided:
  18
  19 \begin{funcdesc}{encode_quopri}{msg}
  20 Encodes the payload into quoted-printable form and sets the
  21 \mailheader{Content-Transfer-Encoding} header to
  22 \code{quoted-printable}\footnote{Note that encoding with
  23 \method{encode_quopri()} also encodes all tabs and space characters in
  24 the data.}.
  25 This is a good encoding to use when most of your payload is normal
  26 printable data, but contains a few unprintable characters.
  27 \end{funcdesc}
  28
  29 \begin{funcdesc}{encode_base64}{msg}
  30 Encodes the payload into base64 form and sets the
  31 \mailheader{Content-Transfer-Encoding} header to
  32 \code{base64}.  This is a good encoding to use when most of your payload
  33 is unprintable data since it is a more compact form than
  34 quoted-printable.  The drawback of base64 encoding is that it
  35 renders the text non-human readable.
  36 \end{funcdesc}
  37
  38 \begin{funcdesc}{encode_7or8bit}{msg}
  39 This doesn't actually modify the message's payload, but it does set
  40 the \mailheader{Content-Transfer-Encoding} header to either \code{7bit} or
  41 \code{8bit} as appropriate, based on the payload data.
  42 \end{funcdesc}
  43
  44 \begin{funcdesc}{encode_noop}{msg}
  45 This does nothing; it doesn't even set the
  46 \mailheader{Content-Transfer-Encoding} header.
  47 \end{funcdesc}