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(python2.1-lib.info)imp
Access the `import' internals
=============================
Access the implementation of the `import' statement.
This module provides an interface to the mechanisms used to implement
the `import' statement. It defines the following constants and
functions:
`get_magic()'
Return the magic string value used to recognize byte-compiled code
files (`.pyc' files). (This value may be different for each
Python version.)
`get_suffixes()'
Return a list of triples, each describing a particular type of
module. Each triple has the form `(SUFFIX, MODE, TYPE)', where
SUFFIX is a string to be appended to the module name to form the
filename to search for, MODE is the mode string to pass to the
built-in `open()' function to open the file (this can be `'r'' for
text files or `'rb'' for binary files), and TYPE is the file type,
which has one of the values `PY_SOURCE', `PY_COMPILED', or
`C_EXTENSION', described below.
`find_module(name[, path])'
Try to find the module NAME on the search path PATH. If PATH is a
list of directory names, each directory is searched for files with
any of the suffixes returned by `get_suffixes()' above. Invalid
names in the list are silently ignored (but all list items must be
strings). If PATH is omitted or `None', the list of directory
names given by `sys.path' is searched, but first it searches a few
special places: it tries to find a built-in module with the given
name (`C_BUILTIN'), then a frozen module (`PY_FROZEN'), and on
some systems some other places are looked in as well (on the Mac,
it looks for a resource (`PY_RESOURCE'); on Windows, it looks in
the registry which may point to a specific file).
If search is successful, the return value is a triple `(FILE,
PATHNAME, DESCRIPTION)' where FILE is an open file object
positioned at the beginning, PATHNAME is the pathname of the file
found, and DESCRIPTION is a triple as contained in the list
returned by `get_suffixes()' describing the kind of module found.
If the module does not live in a file, the returned FILE is
`None', FILENAME is the empty string, and the DESCRIPTION tuple
contains empty strings for its suffix and mode; the module type is
as indicate in parentheses above. If the search is unsuccessful,
`ImportError' is raised. Other exceptions indicate problems with
the arguments or environment.
This function does not handle hierarchical module names (names
containing dots). In order to find P.M, i.e., submodule M of
package P, use `find_module()' and `load_module()' to find and
load package P, and then use `find_module()' with the PATH
argument set to `P.__path__'. When P itself has a dotted name,
apply this recipe recursively.
`load_module(name, file, filename, description)'
Load a module that was previously found by `find_module()' (or by
an otherwise conducted search yielding compatible results). This
function does more than importing the module: if the module was
already imported, it is equivalent to a `reload()' ! The NAME
argument indicates the full module name (including the package
name, if this is a submodule of a package). The FILE argument is
an open file, and FILENAME is the corresponding file name; these
can be `None' and `''', respectively, when the module is not being
loaded from a file. The DESCRIPTION argument is a tuple, as would
be returned by `get_suffixes()', describing what kind of module
must be loaded.
If the load is successful, the return value is the module object;
otherwise, an exception (usually `ImportError') is raised.
*Important:* the caller is responsible for closing the FILE
argument, if it was not `None', even when an exception is raised.
This is best done using a `try' ... `finally' statement.
`new_module(name)'
Return a new empty module object called NAME. This object is
_not_ inserted in `sys.modules'.
The following constants with integer values, defined in this module,
are used to indicate the search result of `find_module()'.
`PY_SOURCE'
The module was found as a source file.
`PY_COMPILED'
The module was found as a compiled code object file.
`C_EXTENSION'
The module was found as dynamically loadable shared library.
`PY_RESOURCE'
The module was found as a Macintosh resource. This value can only
be returned on a Macintosh.
`PKG_DIRECTORY'
The module was found as a package directory.
`C_BUILTIN'
The module was found as a built-in module.
`PY_FROZEN'
The module was found as a frozen module (see `init_frozen()').
The following constant and functions are obsolete; their functionality
is available through `find_module()' or `load_module()'. They are kept
around for backward compatibility:
`SEARCH_ERROR'
Unused.
`init_builtin(name)'
Initialize the built-in module called NAME and return its module
object. If the module was already initialized, it will be
initialized _again_. A few modules cannot be initialized twice --
attempting to initialize these again will raise an `ImportError'
exception. If there is no built-in module called NAME, `None' is
returned.
`init_frozen(name)'
Initialize the frozen module called NAME and return its module
object. If the module was already initialized, it will be
initialized _again_. If there is no frozen module called NAME,
`None' is returned. (Frozen modules are modules written in Python
whose compiled byte-code object is incorporated into a
custom-built Python interpreter by Python's `freeze' utility. See
`Tools/freeze/' for now.)
`is_builtin(name)'
Return `1' if there is a built-in module called NAME which can be
initialized again. Return `-1' if there is a built-in module
called NAME which cannot be initialized again (see
`init_builtin()'). Return `0' if there is no built-in module
called NAME.
`is_frozen(name)'
Return `1' if there is a frozen module (see `init_frozen()')
called NAME, or `0' if there is no such module.
`load_compiled(name, pathname, file)'
Load and initialize a module implemented as a byte-compiled code
file and return its module object. If the module was already
initialized, it will be initialized _again_. The NAME argument is
used to create or access a module object. The PATHNAME argument
points to the byte-compiled code file. The FILE argument is the
byte-compiled code file, open for reading in binary mode, from the
beginning. It must currently be a real file object, not a
user-defined class emulating a file.
`load_dynamic(name, pathname[, file])'
Load and initialize a module implemented as a dynamically loadable
shared library and return its module object. If the module was
already initialized, it will be initialized _again_. Some modules
don't like that and may raise an exception. The PATHNAME argument
must point to the shared library. The NAME argument is used to
construct the name of the initialization function: an external C
function called `initNAME()' in the shared library is called. The
optional FILE argument is ignored. (Note: using shared libraries
is highly system dependent, and not all systems support it.)
`load_source(name, pathname, file)'
Load and initialize a module implemented as a Python source file
and return its module object. If the module was already
initialized, it will be initialized _again_. The NAME argument is
used to create or access a module object. The PATHNAME argument
points to the source file. The 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
`.pyc' or `.pyo') exists, it will be used instead of parsing the
given source file.
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