mirror of https://github.com/python/cpython
parent
0c2af2bef6
commit
bccc64020e
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@ -4,10 +4,9 @@
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\index{import}
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This module provides an interface to the mechanisms used to implement
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the \code{import} statement. It defines the following constants and
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the \keyword{import} statement. It defines the following constants and
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functions:
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\setindexsubitem{(in module imp)}
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\begin{funcdesc}{get_magic}{}
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Return the magic string value used to recognize byte-compiled code
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@ -23,21 +22,21 @@ module name to form the filename to search for, \var{mode} is the mode
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string to pass to the built-in \code{open} function to open the file
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(this can be \code{'r'} for text files or \code{'rb'} for binary
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files), and \var{type} is the file type, which has one of the values
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\code{PY_SOURCE}, \code{PY_COMPILED}, or \code{C_EXTENSION}, defined
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below.
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\constant{PY_SOURCE}, \constant{PY_COMPILED}, or
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\constant{C_EXTENSION}, described below.
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\end{funcdesc}
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\begin{funcdesc}{find_module}{name\optional{, path}}
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Try to find the module \var{name} on the search path \var{path}. If
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\var{path} is a list of directory names, each directory is searched
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for files with any of the suffixes returned by \code{get_suffixes()}
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for files with any of the suffixes returned by \function{get_suffixes()}
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above. Invalid names in the list are silently ignored (but all list
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items must be strings). If \var{path} is omitted or \code{None}, the
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list of directory names given by \code{sys.path} is searched, but
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first it searches a few special places: it tries to find a built-in
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module with the given name (\code{C_BUILTIN}), then a frozen module
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(\code{PY_FROZEN}), and on some systems some other places are looked
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in as well (on the Mac, it looks for a resource (\code{PY_RESOURCE});
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module with the given name (\constant{C_BUILTIN}), then a frozen module
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(\constant{PY_FROZEN}), and on some systems some other places are looked
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in as well (on the Mac, it looks for a resource (\constant{PY_RESOURCE});
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on Windows, it looks in the registry which may point to a specific
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file).
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@ -46,42 +45,44 @@ If search is successful, the return value is a triple
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\var{file} is an open file object positioned at the beginning,
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\var{pathname} is the pathname of the
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file found, and \var{description} is a triple as contained in the list
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returned by \code{get_suffixes} describing the kind of module found.
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returned by \function{get_suffixes()} describing the kind of module found.
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If the module does not live in a file, the returned \var{file} is
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\code{None}, \var{filename} is the empty string, and the
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\var{description} tuple contains empty strings for its suffix and
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mode; the module type is as indicate in parentheses dabove. If the
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search is unsuccessful, \code{ImportError} is raised. Other
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search is unsuccessful, \exception{ImportError} is raised. Other
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exceptions indicate problems with the arguments or environment.
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This function does not handle hierarchical module names (names
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containing dots). In order to find \var{P}.\var{M}, i.e., submodule
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\var{M} of package \var{P}, use \code{find_module()} and
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\code{load_module()} to find and load package \var{P}, and then use
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\code{find_module()} with the \var{path} argument set to
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\var{M} of package \var{P}, use \function{find_module()} and
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\function{load_module()} to find and load package \var{P}, and then use
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\function{find_module()} with the \var{path} argument set to
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\code{\var{P}.__path__}. When \var{P} itself has a dotted name, apply
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this recipe recursively.
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\end{funcdesc}
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\begin{funcdesc}{load_module}{name, file, filename, description}
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Load a module that was previously found by \code{find_module()} (or by
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Load a module that was previously found by \function{find_module()} (or by
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an otherwise conducted search yielding compatible results). This
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function does more than importing the module: if the module was
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already imported, it is equivalent to a \code{reload()}! The
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already imported, it is equivalent to a
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\function{reload()}\bifuncindex{reload}! The
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\var{name} argument indicates the full module name (including the
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package name, if this is a submodule of a package). The \var{file}
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argument is an open file, and \var{filename} is the corresponding
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file name; these can be \code{None} and \code{""}, respectively, when
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file name; these can be \code{None} and \code{''}, respectively, when
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the module is not being loaded from a file. The \var{description}
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argument is a tuple as returned by \code{find_module()} describing what
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kind of module must be loaded.
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argument is a tuple as returned by \function{find_module()} describing
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what kind of module must be loaded.
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If the load is successful, the return value is the module object;
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otherwise, an exception (usually \code{ImportError}) is raised.
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otherwise, an exception (usually \exception{ImportError}) is raised.
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\strong{Important:} the caller is responsible for closing the
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\var{file} argument, if it was not \code{None}, even when an exception
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is raised. This is best done using a try-finally statement.
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is raised. This is best done using a \keyword{try}
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... \keyword{finally} statement.
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\end{funcdesc}
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\begin{funcdesc}{new_module}{name}
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@ -90,7 +91,7 @@ Return a new empty module object called \var{name}. This object is
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\end{funcdesc}
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The following constants with integer values, defined in this module,
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are used to indicate the search result of \code{find_module()}.
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are used to indicate the search result of \function{find_module()}.
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\begin{datadesc}{PY_SOURCE}
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The module was found as a source file.
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@ -118,11 +119,11 @@ The module was found as a built-in module.
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\end{datadesc}
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\begin{datadesc}{PY_FROZEN}
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The module was found as a frozen module (see \code{init_frozen()}).
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The module was found as a frozen module (see \function{init_frozen()}).
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\end{datadesc}
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The following constant and functions are obsolete; their functionality
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is available through \code{find_module()} or \code{load_module()}.
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is available through \function{find_module()} or \function{load_module()}.
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They are kept around for backward compatibility:
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\begin{datadesc}{SEARCH_ERROR}
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@ -133,8 +134,8 @@ Unused.
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Initialize the built-in module called \var{name} and return its module
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object. If the module was already initialized, it will be initialized
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\emph{again}. A few modules cannot be initialized twice --- attempting
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to initialize these again will raise an \code{ImportError} exception.
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If there is no
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to initialize these again will raise an \exception{ImportError}
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exception. If there is no
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built-in module called \var{name}, \code{None} is returned.
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\end{funcdesc}
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@ -144,21 +145,22 @@ object. If the module was already initialized, it will be initialized
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\emph{again}. If there is no frozen module called \var{name},
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\code{None} is returned. (Frozen modules are modules written in
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Python whose compiled byte-code object is incorporated into a
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custom-built Python interpreter by Python's \code{freeze} utility.
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See \file{Tools/freeze} for now.)
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custom-built Python interpreter by Python's \program{freeze} utility.
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See \file{Tools/freeze/} for now.)
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\end{funcdesc}
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\begin{funcdesc}{is_builtin}{name}
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Return \code{1} if there is a built-in module called \var{name} which can be
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initialized again. Return \code{-1} if there is a built-in module
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called \var{name} which cannot be initialized again (see
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\code{init_builtin()}). Return \code{0} if there is no built-in module
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called \var{name}.
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Return \code{1} if there is a built-in module called \var{name} which
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can be initialized again. Return \code{-1} if there is a built-in
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module called \var{name} which cannot be initialized again (see
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\function{init_builtin()}). Return \code{0} if there is no built-in
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module called \var{name}.
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\end{funcdesc}
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\begin{funcdesc}{is_frozen}{name}
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Return \code{1} if there is a frozen module (see \code{init_frozen()})
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called \var{name}, \code{0} if there is no such module.
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Return \code{1} if there is a frozen module (see
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\function{init_frozen()}) called \var{name}, or \code{0} if there is
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no such module.
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\end{funcdesc}
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\begin{funcdesc}{load_compiled}{name, pathname, file}
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@ -180,7 +182,7 @@ already initialized, it will be initialized \emph{again}. Some modules
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don't like that and may raise an exception. The \var{pathname}
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argument must point to the shared library. The \var{name} argument is
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used to construct the name of the initialization function: an external
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C function called \code{init\var{name}()} in the shared library is
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C function called \samp{init\var{name}()} in the shared library is
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called. The optional \var{file} argment is ignored. (Note: using
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shared libraries is highly system dependent, and not all systems
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support it.)
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@ -195,7 +197,7 @@ to the source file. The \var{file} argument is the source
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file, open for reading as text, from the beginning.
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It must currently be a real file
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object, not a user-defined class emulating a file. Note that if a
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properly matching byte-compiled file (with suffix \code{.pyc}) exists,
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properly matching byte-compiled file (with suffix \file{.pyc}) exists,
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it will be used instead of parsing the given source file.
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\end{funcdesc}
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The following function emulates what was the standard import statement
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up to Python 1.4 (i.e., no hierarchical module names). (This
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\emph{implementation} wouldn't work in that version, since
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\code{imp.find_module()} has been extended and
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\code{imp.load_module()} has been added in 1.4.)
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\function{find_module()} has been extended and
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\function{load_module()} has been added in 1.4.)
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\begin{verbatim}
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import imp import sys
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\end{verbatim}
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A more complete example that implements hierarchical module names and
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includes a \code{reload()} function can be found in the standard
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module \code{knee}\refstmodindex{knee} (which is intended as an
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example only -- don't rely on any part of it being a standard
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interface).
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includes a \function{reload()}\bifuncindex{reload} function can be
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found in the standard module \module{knee}\refstmodindex{knee} (which
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is intended as an example only --- don't rely on any part of it being
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a standard interface).
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@ -4,10 +4,9 @@
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\index{import}
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This module provides an interface to the mechanisms used to implement
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the \code{import} statement. It defines the following constants and
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the \keyword{import} statement. It defines the following constants and
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functions:
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\setindexsubitem{(in module imp)}
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\begin{funcdesc}{get_magic}{}
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Return the magic string value used to recognize byte-compiled code
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@ -23,21 +22,21 @@ module name to form the filename to search for, \var{mode} is the mode
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string to pass to the built-in \code{open} function to open the file
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(this can be \code{'r'} for text files or \code{'rb'} for binary
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files), and \var{type} is the file type, which has one of the values
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\code{PY_SOURCE}, \code{PY_COMPILED}, or \code{C_EXTENSION}, defined
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below.
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\constant{PY_SOURCE}, \constant{PY_COMPILED}, or
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\constant{C_EXTENSION}, described below.
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\end{funcdesc}
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\begin{funcdesc}{find_module}{name\optional{, path}}
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Try to find the module \var{name} on the search path \var{path}. If
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\var{path} is a list of directory names, each directory is searched
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for files with any of the suffixes returned by \code{get_suffixes()}
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for files with any of the suffixes returned by \function{get_suffixes()}
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above. Invalid names in the list are silently ignored (but all list
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items must be strings). If \var{path} is omitted or \code{None}, the
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list of directory names given by \code{sys.path} is searched, but
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first it searches a few special places: it tries to find a built-in
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module with the given name (\code{C_BUILTIN}), then a frozen module
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(\code{PY_FROZEN}), and on some systems some other places are looked
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in as well (on the Mac, it looks for a resource (\code{PY_RESOURCE});
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module with the given name (\constant{C_BUILTIN}), then a frozen module
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(\constant{PY_FROZEN}), and on some systems some other places are looked
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in as well (on the Mac, it looks for a resource (\constant{PY_RESOURCE});
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on Windows, it looks in the registry which may point to a specific
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file).
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@ -46,42 +45,44 @@ If search is successful, the return value is a triple
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\var{file} is an open file object positioned at the beginning,
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\var{pathname} is the pathname of the
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file found, and \var{description} is a triple as contained in the list
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returned by \code{get_suffixes} describing the kind of module found.
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returned by \function{get_suffixes()} describing the kind of module found.
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If the module does not live in a file, the returned \var{file} is
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\code{None}, \var{filename} is the empty string, and the
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\var{description} tuple contains empty strings for its suffix and
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mode; the module type is as indicate in parentheses dabove. If the
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search is unsuccessful, \code{ImportError} is raised. Other
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search is unsuccessful, \exception{ImportError} is raised. Other
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exceptions indicate problems with the arguments or environment.
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This function does not handle hierarchical module names (names
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containing dots). In order to find \var{P}.\var{M}, i.e., submodule
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\var{M} of package \var{P}, use \code{find_module()} and
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\code{load_module()} to find and load package \var{P}, and then use
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\code{find_module()} with the \var{path} argument set to
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\var{M} of package \var{P}, use \function{find_module()} and
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\function{load_module()} to find and load package \var{P}, and then use
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\function{find_module()} with the \var{path} argument set to
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\code{\var{P}.__path__}. When \var{P} itself has a dotted name, apply
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this recipe recursively.
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\end{funcdesc}
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\begin{funcdesc}{load_module}{name, file, filename, description}
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Load a module that was previously found by \code{find_module()} (or by
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Load a module that was previously found by \function{find_module()} (or by
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an otherwise conducted search yielding compatible results). This
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function does more than importing the module: if the module was
|
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already imported, it is equivalent to a \code{reload()}! The
|
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already imported, it is equivalent to a
|
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\function{reload()}\bifuncindex{reload}! The
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\var{name} argument indicates the full module name (including the
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package name, if this is a submodule of a package). The \var{file}
|
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argument is an open file, and \var{filename} is the corresponding
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file name; these can be \code{None} and \code{""}, respectively, when
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file name; these can be \code{None} and \code{''}, respectively, when
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the module is not being loaded from a file. The \var{description}
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argument is a tuple as returned by \code{find_module()} describing what
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kind of module must be loaded.
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argument is a tuple as returned by \function{find_module()} describing
|
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what kind of module must be loaded.
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If the load is successful, the return value is the module object;
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otherwise, an exception (usually \code{ImportError}) is raised.
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otherwise, an exception (usually \exception{ImportError}) is raised.
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\strong{Important:} the caller is responsible for closing the
|
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\var{file} argument, if it was not \code{None}, even when an exception
|
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is raised. This is best done using a try-finally statement.
|
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is raised. This is best done using a \keyword{try}
|
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... \keyword{finally} statement.
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\end{funcdesc}
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\begin{funcdesc}{new_module}{name}
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|
@ -90,7 +91,7 @@ Return a new empty module object called \var{name}. This object is
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\end{funcdesc}
|
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|
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The following constants with integer values, defined in this module,
|
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are used to indicate the search result of \code{find_module()}.
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are used to indicate the search result of \function{find_module()}.
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\begin{datadesc}{PY_SOURCE}
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The module was found as a source file.
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|
@ -118,11 +119,11 @@ The module was found as a built-in module.
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\end{datadesc}
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\begin{datadesc}{PY_FROZEN}
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The module was found as a frozen module (see \code{init_frozen()}).
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The module was found as a frozen module (see \function{init_frozen()}).
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\end{datadesc}
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|
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The following constant and functions are obsolete; their functionality
|
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is available through \code{find_module()} or \code{load_module()}.
|
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is available through \function{find_module()} or \function{load_module()}.
|
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They are kept around for backward compatibility:
|
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\begin{datadesc}{SEARCH_ERROR}
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|
@ -133,8 +134,8 @@ Unused.
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Initialize the built-in module called \var{name} and return its module
|
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object. If the module was already initialized, it will be initialized
|
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\emph{again}. A few modules cannot be initialized twice --- attempting
|
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to initialize these again will raise an \code{ImportError} exception.
|
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If there is no
|
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to initialize these again will raise an \exception{ImportError}
|
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exception. If there is no
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built-in module called \var{name}, \code{None} is returned.
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\end{funcdesc}
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|
@ -144,21 +145,22 @@ object. If the module was already initialized, it will be initialized
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\emph{again}. If there is no frozen module called \var{name},
|
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\code{None} is returned. (Frozen modules are modules written in
|
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Python whose compiled byte-code object is incorporated into a
|
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custom-built Python interpreter by Python's \code{freeze} utility.
|
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See \file{Tools/freeze} for now.)
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custom-built Python interpreter by Python's \program{freeze} utility.
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See \file{Tools/freeze/} for now.)
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\end{funcdesc}
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\begin{funcdesc}{is_builtin}{name}
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Return \code{1} if there is a built-in module called \var{name} which can be
|
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initialized again. Return \code{-1} if there is a built-in module
|
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called \var{name} which cannot be initialized again (see
|
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\code{init_builtin()}). Return \code{0} if there is no built-in module
|
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called \var{name}.
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Return \code{1} if there is a built-in module called \var{name} which
|
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can be initialized again. Return \code{-1} if there is a built-in
|
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module called \var{name} which cannot be initialized again (see
|
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\function{init_builtin()}). Return \code{0} if there is no built-in
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module called \var{name}.
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\end{funcdesc}
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\begin{funcdesc}{is_frozen}{name}
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Return \code{1} if there is a frozen module (see \code{init_frozen()})
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called \var{name}, \code{0} if there is no such module.
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Return \code{1} if there is a frozen module (see
|
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\function{init_frozen()}) called \var{name}, or \code{0} if there is
|
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no such module.
|
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\end{funcdesc}
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\begin{funcdesc}{load_compiled}{name, pathname, file}
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|
@ -180,7 +182,7 @@ already initialized, it will be initialized \emph{again}. Some modules
|
|||
don't like that and may raise an exception. The \var{pathname}
|
||||
argument must point to the shared library. The \var{name} argument is
|
||||
used to construct the name of the initialization function: an external
|
||||
C function called \code{init\var{name}()} in the shared library is
|
||||
C function called \samp{init\var{name}()} in the shared library is
|
||||
called. The optional \var{file} argment is ignored. (Note: using
|
||||
shared libraries is highly system dependent, and not all systems
|
||||
support it.)
|
||||
|
@ -195,7 +197,7 @@ to the source file. The \var{file} argument is the source
|
|||
file, open for reading as text, from the beginning.
|
||||
It must currently be a real file
|
||||
object, not a user-defined class emulating a file. Note that if a
|
||||
properly matching byte-compiled file (with suffix \code{.pyc}) exists,
|
||||
properly matching byte-compiled file (with suffix \file{.pyc}) exists,
|
||||
it will be used instead of parsing the given source file.
|
||||
\end{funcdesc}
|
||||
|
||||
|
@ -206,8 +208,8 @@ it will be used instead of parsing the given source file.
|
|||
The following function emulates what was the standard import statement
|
||||
up to Python 1.4 (i.e., no hierarchical module names). (This
|
||||
\emph{implementation} wouldn't work in that version, since
|
||||
\code{imp.find_module()} has been extended and
|
||||
\code{imp.load_module()} has been added in 1.4.)
|
||||
\function{find_module()} has been extended and
|
||||
\function{load_module()} has been added in 1.4.)
|
||||
|
||||
\begin{verbatim}
|
||||
import imp import sys
|
||||
|
@ -233,7 +235,7 @@ def __import__(name, globals=None, locals=None, fromlist=None):
|
|||
\end{verbatim}
|
||||
|
||||
A more complete example that implements hierarchical module names and
|
||||
includes a \code{reload()} function can be found in the standard
|
||||
module \code{knee}\refstmodindex{knee} (which is intended as an
|
||||
example only -- don't rely on any part of it being a standard
|
||||
interface).
|
||||
includes a \function{reload()}\bifuncindex{reload} function can be
|
||||
found in the standard module \module{knee}\refstmodindex{knee} (which
|
||||
is intended as an example only --- don't rely on any part of it being
|
||||
a standard interface).
|
||||
|
|
Loading…
Reference in New Issue