Doc/lib/libni.tex

   1 \section{\module{ni} ---
   2          None}
   3 \declaremodule{standard}{ni}
   4
   5 \modulesynopsis{None}
   6
   7
   8 \strong{Warning: This module is obsolete.}  As of Python 1.5a4,
   9 package support (with different semantics for \code{__init__} and no
  10 support for \code{__domain__} or \code{__}) is built in the
  11 interpreter.  The ni module is retained only for backward
  12 compatibility.  As of Python 1.5b2, it has been renamed to \code{ni1};
  13 if you really need it, you can use \code{import ni1}, but the
  14 recommended approach is to rely on the built-in package support,
  15 converting existing packages if needed.  Note that mixing \code{ni}
  16 and the built-in package support doesn't work: once you import
  17 \code{ni}, all packages use it.
  18
  19 The \code{ni} module defines a new importing scheme, which supports
  20 packages containing several Python modules.  To enable package
  21 support, execute \code{import ni} before importing any packages.  Importing
  22 this module automatically installs the relevant import hooks.  There
  23 are no publicly-usable functions or variables in the \code{ni} module.
  24
  25 To create a package named \code{spam} containing sub-modules \code{ham}, \code{bacon} and
  26 \code{eggs}, create a directory \file{spam} somewhere on Python's module search
  27 path, as given in \code{sys.path}.  Then, create files called \file{ham.py}, \file{bacon.py} and
  28 \file{eggs.py} inside \file{spam}.
  29
  30 To import module \code{ham} from package \code{spam} and use function
  31 \code{hamneggs()} from that module, you can use any of the following
  32 possibilities:
  33
  34 \begin{verbatim}
  35 import spam.ham         # *not* "import spam" !!!
  36 spam.ham.hamneggs()
  37 \end{verbatim}
  38 %
  39 \begin{verbatim}
  40 from spam import ham
  41 ham.hamneggs()
  42 \end{verbatim}
  43 %
  44 \begin{verbatim}
  45 from spam.ham import hamneggs
  46 hamneggs()
  47 \end{verbatim}
  48 %
  49 \code{import spam} creates an
  50 empty package named \code{spam} if one does not already exist, but it does
  51 \emph{not} automatically import \code{spam}'s submodules.
  52 The only submodule that is guaranteed to be imported is
  53 \code{spam.__init__}, if it exists; it would be in a file named
  54 \file{__init__.py} in the \file{spam} directory.  Note that
  55 \code{spam.__init__} is a submodule of package spam.  It can refer to
  56 spam's namespace as \code{__} (two underscores):
  57
  58 \begin{verbatim}
  59 __.spam_inited = 1              # Set a package-level variable
  60 \end{verbatim}
  61 %
  62 Additional initialization code (setting up variables, importing other
  63 submodules) can be performed in \file{spam/__init__.py}.