61 lines
2.4 KiB
TeX
61 lines
2.4 KiB
TeX
\section{Standard Module \sectcode{ni}}
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\label{module-ni}
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\stmodindex{ni}
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\strong{Warning: This module is obsolete.} As of Python 1.5a4,
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package support (with different semantics for \code{__init__} and no
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support for \code{__domain__} or \code{__}) is built in the
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interpreter. The ni module is retained only for backward
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compatibility. As of Python 1.5b2, it has been renamed to \code{ni1};
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if you really need it, you can use \code{import ni1}, but the
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recommended approach is to rely on the built-in package support,
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converting existing packages if needed. Note that mixing \code{ni}
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and the built-in package support doesn't work: once you import
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\code{ni}, all packages use it.
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The \code{ni} module defines a new importing scheme, which supports
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packages containing several Python modules. To enable package
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support, execute \code{import ni} before importing any packages. Importing
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this module automatically installs the relevant import hooks. There
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are no publicly-usable functions or variables in the \code{ni} module.
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To create a package named \code{spam} containing sub-modules \code{ham}, \code{bacon} and
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\code{eggs}, create a directory \file{spam} somewhere on Python's module search
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path, as given in \code{sys.path}. Then, create files called \file{ham.py}, \file{bacon.py} and
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\file{eggs.py} inside \file{spam}.
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To import module \code{ham} from package \code{spam} and use function
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\code{hamneggs()} from that module, you can use any of the following
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possibilities:
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\bcode\begin{verbatim}
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import spam.ham # *not* "import spam" !!!
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spam.ham.hamneggs()
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\end{verbatim}\ecode
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%
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\bcode\begin{verbatim}
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from spam import ham
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ham.hamneggs()
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\end{verbatim}\ecode
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%
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\bcode\begin{verbatim}
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from spam.ham import hamneggs
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hamneggs()
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\end{verbatim}\ecode
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%
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\code{import spam} creates an
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empty package named \code{spam} if one does not already exist, but it does
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\emph{not} automatically import \code{spam}'s submodules.
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The only submodule that is guaranteed to be imported is
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\code{spam.__init__}, if it exists; it would be in a file named
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\file{__init__.py} in the \file{spam} directory. Note that
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\code{spam.__init__} is a submodule of package spam. It can refer to
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spam's namespace as \code{__} (two underscores):
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\bcode\begin{verbatim}
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__.spam_inited = 1 # Set a package-level variable
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\end{verbatim}\ecode
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%
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Additional initialization code (setting up variables, importing other
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submodules) can be performed in \file{spam/__init__.py}.
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