Doc/lib/emailutil.tex

   1 \declaremodule{standard}{email.Utils}
   2 \modulesynopsis{Miscellaneous email package utilities.}
   3
   4 There are several useful utilities provided with the \module{email}
   5 package.
   6
   7 \begin{funcdesc}{quote}{str}
   8 Return a new string with backslashes in \var{str} replaced by two
   9 backslashes and double quotes replaced by backslash-double quote.
  10 \end{funcdesc}
  11
  12 \begin{funcdesc}{unquote}{str}
  13 Return a new string which is an \emph{unquoted} version of \var{str}.
  14 If \var{str} ends and begins with double quotes, they are stripped
  15 off.  Likewise if \var{str} ends and begins with angle brackets, they
  16 are stripped off.
  17 \end{funcdesc}
  18
  19 \begin{funcdesc}{parseaddr}{address}
  20 Parse address -- which should be the value of some address-containing
  21 field such as \mailheader{To} or \mailheader{Cc} -- into its constituent
  22 \emph{realname} and \emph{email address} parts.  Returns a tuple of that
  23 information, unless the parse fails, in which case a 2-tuple of
  24 \code{(None, None)} is returned.
  25 \end{funcdesc}
  26
  27 \begin{funcdesc}{dump_address_pair}{pair}
  28 The inverse of \method{parseaddr()}, this takes a 2-tuple of the form
  29 \code{(realname, email_address)} and returns the string value suitable
  30 for a \mailheader{To} or \mailheader{Cc} header.  If the first element of
  31 \var{pair} is false, then the second element is returned unmodified.
  32 \end{funcdesc}
  33
  34 \begin{funcdesc}{getaddresses}{fieldvalues}
  35 This method returns a list of 2-tuples of the form returned by
  36 \code{parseaddr()}.  \var{fieldvalues} is a sequence of header field
  37 values as might be returned by \method{Message.getall()}.  Here's a
  38 simple example that gets all the recipients of a message:
  39
  40 \begin{verbatim}
  41 from email.Utils import getaddresses
  42
  43 tos = msg.get_all('to', [])
  44 ccs = msg.get_all('cc', [])
  45 resent_tos = msg.get_all('resent-to', [])
  46 resent_ccs = msg.get_all('resent-cc', [])
  47 all_recipients = getaddresses(tos + ccs + resent_tos + resent_ccs)
  48 \end{verbatim}
  49 \end{funcdesc}
  50
  51 \begin{funcdesc}{decode}{s}
  52 This method decodes a string according to the rules in \rfc{2047}.  It
  53 returns the decoded string as a Python unicode string.
  54 \end{funcdesc}
  55
  56 \begin{funcdesc}{encode}{s\optional{, charset\optional{, encoding}}}
  57 This method encodes a string according to the rules in \rfc{2047}.  It
  58 is not actually the inverse of \function{decode()} since it doesn't
  59 handle multiple character sets or multiple string parts needing
  60 encoding.  In fact, the input string \var{s} must already be encoded
  61 in the \var{charset} character set (Python can't reliably guess what
  62 character set a string might be encoded in).  The default
  63 \var{charset} is \samp{iso-8859-1}.
  64
  65 \var{encoding} must be either the letter \character{q} for
  66 Quoted-Printable or \character{b} for Base64 encoding.  If
  67 neither, a \exception{ValueError} is raised.  Both the \var{charset} and
  68 the \var{encoding} strings are case-insensitive, and coerced to lower
  69 case in the returned string.
  70 \end{funcdesc}
  71
  72 \begin{funcdesc}{parsedate}{date}
  73 Attempts to parse a date according to the rules in \rfc{2822}.
  74 however, some mailers don't follow that format as specified, so
  75 \function{parsedate()} tries to guess correctly in such cases.
  76 \var{date} is a string containing an \rfc{2822} date, such as
  77 \code{"Mon, 20 Nov 1995 19:12:08 -0500"}.  If it succeeds in parsing
  78 the date, \function{parsedate()} returns a 9-tuple that can be passed
  79 directly to \function{time.mktime()}; otherwise \code{None} will be
  80 returned.  Note that fields 6, 7, and 8 of the result tuple are not
  81 usable.
  82 \end{funcdesc}
  83
  84 \begin{funcdesc}{parsedate_tz}{date}
  85 Performs the same function as \function{parsedate()}, but returns
  86 either \code{None} or a 10-tuple; the first 9 elements make up a tuple
  87 that can be passed directly to \function{time.mktime()}, and the tenth
  88 is the offset of the date's timezone from UTC (which is the official
  89 term for Greenwich Mean Time)\footnote{Note that the sign of the timezone
  90 offset is the opposite of the sign of the \code{time.timezone}
  91 variable for the same timezone; the latter variable follows the
  92 \POSIX{} standard while this module follows \rfc{2822}.}.  If the input
  93 string has no timezone, the last element of the tuple returned is
  94 \code{None}.  Note that fields 6, 7, and 8 of the result tuple are not
  95 usable.
  96 \end{funcdesc}
  97
  98 \begin{funcdesc}{mktime_tz}{tuple}
  99 Turn a 10-tuple as returned by \function{parsedate_tz()} into a UTC
 100 timestamp.  It the timezone item in the tuple is \code{None}, assume
 101 local time.  Minor deficiency: \function{mktime_tz()} interprets the
 102 first 8 elements of \var{tuple} as a local time and then compensates
 103 for the timezone difference.  This may yield a slight error around
 104 changes in daylight savings time, though not worth worrying about for
 105 common use.
 106 \end{funcdesc}
 107
 108 \begin{funcdesc}{formatdate}{\optional{timeval\optional{, localtime}}}
 109 Returns a date string as per Internet standard \rfc{2822}, e.g.:
 110
 111 \begin{verbatim}
 112 Fri, 09 Nov 2001 01:08:47 -0000
 113 \end{verbatim}
 114
 115 Optional \var{timeval} if given is a floating point time value as
 116 accepted by \function{time.gmtime()} and \function{time.localtime()},
 117 otherwise the current time is used.
 118
 119 Optional \var{localtime} is a flag that when true, interprets
 120 \var{timeval}, and returns a date relative to the local timezone
 121 instead of UTC, properly taking daylight savings time into account.
 122 \end{funcdesc}