with PEP 302. This was fixed by adding an ``imp.NullImporter`` type that is used in ``sys.path_importer_cache`` to cache non-directory paths and avoid excessive filesystem operations during imports.
This commit is contained in:
Phillip J. Eby
parent
944f3b6ecb
commit
f7575d0cb7
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@ -232,6 +232,24 @@ properly matching byte-compiled file (with suffix \file{.pyc} or
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source file.
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\end{funcdesc}
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\begin{classdesc}{NullImporter}{path_string}
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The \class{NullImporter} type is a \pep{302} import hook that handles
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non-directory path strings by failing to find any modules. Calling this
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type with an existing directory or empty string raises
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\exception{ImportError}. Otherwise, a \class{NullImporter} instance is
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returned.
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Python adds instances of this type to \code{sys.path_importer_cache} for
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any path entries that are not directories and are not handled by any other
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path hooks on \code{sys.path_hooks}. Instances have only one method:
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\begin{methoddesc}{find_module}{fullname \optional{, path}}
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This method always returns \code{None}, indicating that the requested
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module could not be found.
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\end{methoddesc}
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\versionadded{2.5}
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\end{classdesc}
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\subsection{Examples}
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\label{examples-imp}
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@ -257,7 +275,7 @@ def __import__(name, globals=None, locals=None, fromlist=None):
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# there's a problem we can't handle -- let the caller handle it.
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fp, pathname, description = imp.find_module(name)
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try:
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return imp.load_module(name, fp, pathname, description)
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finally:
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@ -381,9 +381,7 @@ def get_importer(path_item):
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importer = None
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sys.path_importer_cache.setdefault(path_item, importer)
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# The boolean values are used for caching valid and invalid
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# file paths for the built-in import machinery
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if importer in (None, True, False):
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if importer is None:
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try:
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importer = ImpImporter(path_item)
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except ImportError:
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@ -12,6 +12,11 @@ What's New in Python 2.5 release candidate 1?
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Core and builtins
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-----------------
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- Bug #1529871: The speed enhancement patch #921466 broke Python's compliance
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with PEP 302. This was fixed by adding an ``imp.NullImporter`` type that is
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used in ``sys.path_importer_cache`` to cache non-directory paths and avoid
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excessive filesystem operations during imports.
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- Bug #1521947: When checking for overflow, ``PyOS_strtol()`` used some
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operations on signed longs that are formally undefined by C.
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Unfortunately, at least one compiler now cares about that, so complicated
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@ -106,10 +111,14 @@ Library
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Extension Modules
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-----------------
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<<<<<<< .mine
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- Bug #1471938: Fix curses module build problem on Solaris 8; patch by
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=======
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- The ``__reduce__()`` method of the new ``collections.defaultdict`` had
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a memory leak, affecting pickles and deep copies.
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- Bug #1471938: Fix curses module build problem on Solaris 8; patch by
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>>>>>>> .r50915
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Paul Eggert.
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- Patch #1448199: Release interpreter lock in _winreg.ConnectRegistry.
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166
Python/import.c
166
Python/import.c
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@ -98,6 +98,8 @@ static const struct filedescr _PyImport_StandardFiletab[] = {
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};
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#endif
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static PyTypeObject NullImporterType; /* Forward reference */
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/* Initialize things */
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void
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@ -155,6 +157,8 @@ _PyImportHooks_Init(void)
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/* adding sys.path_hooks and sys.path_importer_cache, setting up
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zipimport */
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if (PyType_Ready(&NullImporterType) < 0)
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goto error;
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if (Py_VerboseFlag)
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PySys_WriteStderr("# installing zipimport hook\n");
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@ -180,9 +184,11 @@ _PyImportHooks_Init(void)
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if (err) {
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error:
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PyErr_Print();
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Py_FatalError("initializing sys.meta_path, sys.path_hooks or "
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"path_importer_cache failed");
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Py_FatalError("initializing sys.meta_path, sys.path_hooks, "
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"path_importer_cache, or NullImporter failed"
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);
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}
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zimpimport = PyImport_ImportModule("zipimport");
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if (zimpimport == NULL) {
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PyErr_Clear(); /* No zip import module -- okay */
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@ -1058,9 +1064,18 @@ get_path_importer(PyObject *path_importer_cache, PyObject *path_hooks,
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}
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PyErr_Clear();
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}
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if (importer == NULL)
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importer = Py_None;
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else if (importer != Py_None) {
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if (importer == NULL) {
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importer = PyObject_CallFunctionObjArgs(
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(PyObject *)&NullImporterType, p, NULL
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);
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if (importer == NULL) {
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if (PyErr_ExceptionMatches(PyExc_ImportError)) {
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PyErr_Clear();
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return Py_None;
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}
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}
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}
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if (importer != NULL) {
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int err = PyDict_SetItem(path_importer_cache, p, importer);
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Py_DECREF(importer);
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if (err != 0)
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@ -1248,35 +1263,7 @@ find_module(char *fullname, char *subname, PyObject *path, char *buf,
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return NULL;
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}
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/* Note: importer is a borrowed reference */
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if (importer == Py_False) {
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/* Cached as not being a valid dir. */
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Py_XDECREF(copy);
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continue;
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}
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else if (importer == Py_True) {
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/* Cached as being a valid dir, so just
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* continue below. */
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}
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else if (importer == Py_None) {
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/* No importer was found, so it has to be a file.
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* Check if the directory is valid.
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* Note that the empty string is a valid path, but
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* not stat'able, hence the check for len. */
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#ifdef HAVE_STAT
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if (len && stat(buf, &statbuf) != 0) {
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/* Directory does not exist. */
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PyDict_SetItem(path_importer_cache,
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v, Py_False);
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Py_XDECREF(copy);
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continue;
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} else {
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PyDict_SetItem(path_importer_cache,
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v, Py_True);
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}
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#endif
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}
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else {
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/* A real import hook importer was found. */
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if (importer != Py_None) {
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PyObject *loader;
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loader = PyObject_CallMethod(importer,
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"find_module",
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@ -2935,11 +2922,120 @@ setint(PyObject *d, char *name, int value)
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return err;
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}
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typedef struct {
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PyObject_HEAD
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} NullImporter;
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static int
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NullImporter_init(NullImporter *self, PyObject *args, PyObject *kwds)
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{
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char *path;
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if (!_PyArg_NoKeywords("NullImporter()", kwds))
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return -1;
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if (!PyArg_ParseTuple(args, "s:NullImporter",
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&path))
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return -1;
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if (strlen(path) == 0) {
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PyErr_SetString(PyExc_ImportError, "empty pathname");
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return -1;
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} else {
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#ifndef RISCOS
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struct stat statbuf;
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int rv;
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rv = stat(path, &statbuf);
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if (rv == 0) {
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/* it exists */
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if (S_ISDIR(statbuf.st_mode)) {
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/* it's a directory */
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PyErr_SetString(PyExc_ImportError,
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"existing directory");
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return -1;
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}
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}
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#else
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if (object_exists(path)) {
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/* it exists */
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if (isdir(path)) {
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/* it's a directory */
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PyErr_SetString(PyExc_ImportError,
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"existing directory");
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return -1;
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}
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}
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#endif
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}
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return 0;
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}
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static PyObject *
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NullImporter_find_module(NullImporter *self, PyObject *args)
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{
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Py_RETURN_NONE;
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}
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static PyMethodDef NullImporter_methods[] = {
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{"find_module", (PyCFunction)NullImporter_find_module, METH_VARARGS,
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"Always return None"
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},
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{NULL} /* Sentinel */
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};
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static PyTypeObject NullImporterType = {
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PyObject_HEAD_INIT(NULL)
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0, /*ob_size*/
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"imp.NullImporter", /*tp_name*/
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sizeof(NullImporter), /*tp_basicsize*/
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0, /*tp_itemsize*/
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0, /*tp_dealloc*/
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0, /*tp_print*/
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0, /*tp_getattr*/
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0, /*tp_setattr*/
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0, /*tp_compare*/
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0, /*tp_repr*/
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0, /*tp_as_number*/
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0, /*tp_as_sequence*/
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0, /*tp_as_mapping*/
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0, /*tp_hash */
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0, /*tp_call*/
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0, /*tp_str*/
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0, /*tp_getattro*/
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0, /*tp_setattro*/
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0, /*tp_as_buffer*/
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Py_TPFLAGS_DEFAULT, /*tp_flags*/
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"Null importer object", /* tp_doc */
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0, /* tp_traverse */
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0, /* tp_clear */
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0, /* tp_richcompare */
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0, /* tp_weaklistoffset */
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0, /* tp_iter */
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0, /* tp_iternext */
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NullImporter_methods, /* tp_methods */
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0, /* tp_members */
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0, /* tp_getset */
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0, /* tp_base */
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0, /* tp_dict */
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0, /* tp_descr_get */
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0, /* tp_descr_set */
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0, /* tp_dictoffset */
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(initproc)NullImporter_init, /* tp_init */
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0, /* tp_alloc */
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PyType_GenericNew /* tp_new */
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};
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PyMODINIT_FUNC
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initimp(void)
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{
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PyObject *m, *d;
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if (PyType_Ready(&NullImporterType) < 0)
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goto failure;
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m = Py_InitModule4("imp", imp_methods, doc_imp,
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NULL, PYTHON_API_VERSION);
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if (m == NULL)
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@ -2957,6 +3053,8 @@ initimp(void)
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if (setint(d, "PY_CODERESOURCE", PY_CODERESOURCE) < 0) goto failure;
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if (setint(d, "IMP_HOOK", IMP_HOOK) < 0) goto failure;
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Py_INCREF(&NullImporterType);
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PyModule_AddObject(m, "NullImporter", (PyObject *)&NullImporterType);
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failure:
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;
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}
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