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| 55 | <H1><A NAME="SECTION007300000000000000000"></A><A NAME="importing"></A> |
| 56 | <BR> |
| 57 | 5.3 Importing Modules |
| 58 | </H1> |
| 59 | |
| 60 | <P> |
| 61 | <dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline"><td><nobr>PyObject* <b><tt id='l2h-170' xml:id='l2h-170' class="cfunction">PyImport_ImportModule</tt></b>(</nobr></td><td>char *<var>name</var>)</td></tr></table></dt> |
| 62 | <dd> |
| 63 | <div class="refcount-info"> |
| 64 | <span class="label">Return value:</span> |
| 65 | <span class="value">New reference.</span> |
| 66 | </div> |
| 67 | This is a simplified interface to |
| 68 | <tt class="cfunction">PyImport_ImportModuleEx()</tt> below, leaving the |
| 69 | <var>globals</var> and <var>locals</var> arguments set to <tt class="constant">NULL</tt>. When the |
| 70 | <var>name</var> argument contains a dot (when it specifies a submodule of |
| 71 | a package), the <var>fromlist</var> argument is set to the list |
| 72 | <code>['*']</code> so that the return value is the named module rather |
| 73 | than the top-level package containing it as would otherwise be the |
| 74 | case. (Unfortunately, this has an additional side effect when |
| 75 | <var>name</var> in fact specifies a subpackage instead of a submodule: |
| 76 | the submodules specified in the package's <code>__all__</code> variable |
| 77 | are <a id='l2h-196' xml:id='l2h-196'></a> |
| 78 | <a id='l2h-172' xml:id='l2h-172'></a>loaded.) Return |
| 79 | a new reference to the imported module, or <tt class="constant">NULL</tt> with an exception |
| 80 | set on failure. Before Python 2.4, the module may still be created in |
| 81 | the failure case -- examine <code>sys.modules</code> to find out. Starting |
| 82 | with Python 2.4, a failing import of a module no longer leaves the |
| 83 | module in <code>sys.modules</code>. |
| 84 | |
| 85 | <span class="versionnote">Changed in version 2.4: |
| 86 | failing imports remove incomplete module objects.</span> |
| 87 | |
| 88 | <a id='l2h-174' xml:id='l2h-174'></a></dd></dl> |
| 89 | |
| 90 | <P> |
| 91 | <dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline"><td><nobr>PyObject* <b><tt id='l2h-175' xml:id='l2h-175' class="cfunction">PyImport_ImportModuleEx</tt></b>(</nobr></td><td>char *<var>name</var>, |
| 92 | PyObject *<var>globals</var>, PyObject *<var>locals</var>, PyObject *<var>fromlist</var>)</td></tr></table></dt> |
| 93 | <dd> |
| 94 | <div class="refcount-info"> |
| 95 | <span class="label">Return value:</span> |
| 96 | <span class="value">New reference.</span> |
| 97 | </div> |
| 98 | Import a module. This is best described by referring to the |
| 99 | built-in Python function |
| 100 | <tt class="function">__import__()</tt><a id='l2h-176' xml:id='l2h-176'></a>, as the standard |
| 101 | <tt class="function">__import__()</tt> function calls this function directly. |
| 102 | |
| 103 | <P> |
| 104 | The return value is a new reference to the imported module or |
| 105 | top-level package, or <tt class="constant">NULL</tt> with an exception set on failure (before |
| 106 | Python 2.4, the |
| 107 | module may still be created in this case). Like for |
| 108 | <tt class="function">__import__()</tt>, the return value when a submodule of a |
| 109 | package was requested is normally the top-level package, unless a |
| 110 | non-empty <var>fromlist</var> was given. |
| 111 | |
| 112 | <span class="versionnote">Changed in version 2.4: |
| 113 | failing imports remove incomplete module objects.</span> |
| 114 | |
| 115 | </dd></dl> |
| 116 | |
| 117 | <P> |
| 118 | <dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline"><td><nobr>PyObject* <b><tt id='l2h-177' xml:id='l2h-177' class="cfunction">PyImport_Import</tt></b>(</nobr></td><td>PyObject *<var>name</var>)</td></tr></table></dt> |
| 119 | <dd> |
| 120 | <div class="refcount-info"> |
| 121 | <span class="label">Return value:</span> |
| 122 | <span class="value">New reference.</span> |
| 123 | </div> |
| 124 | This is a higher-level interface that calls the current ``import |
| 125 | hook function''. It invokes the <tt class="function">__import__()</tt> function |
| 126 | from the <code>__builtins__</code> of the current globals. This means |
| 127 | that the import is done using whatever import hooks are installed in |
| 128 | the current environment, e.g. by <tt class="module">rexec</tt><a id='l2h-197' xml:id='l2h-197'></a> |
| 129 | or <tt class="module">ihooks</tt><a id='l2h-198' xml:id='l2h-198'></a>. |
| 130 | </dd></dl> |
| 131 | |
| 132 | <P> |
| 133 | <dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline"><td><nobr>PyObject* <b><tt id='l2h-178' xml:id='l2h-178' class="cfunction">PyImport_ReloadModule</tt></b>(</nobr></td><td>PyObject *<var>m</var>)</td></tr></table></dt> |
| 134 | <dd> |
| 135 | <div class="refcount-info"> |
| 136 | <span class="label">Return value:</span> |
| 137 | <span class="value">New reference.</span> |
| 138 | </div> |
| 139 | Reload a module. This is best described by referring to the |
| 140 | built-in Python function <tt class="function">reload()</tt><a id='l2h-179' xml:id='l2h-179'></a>, as |
| 141 | the standard <tt class="function">reload()</tt> function calls this function |
| 142 | directly. Return a new reference to the reloaded module, or <tt class="constant">NULL</tt> |
| 143 | with an exception set on failure (the module still exists in this |
| 144 | case). |
| 145 | </dd></dl> |
| 146 | |
| 147 | <P> |
| 148 | <dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline"><td><nobr>PyObject* <b><tt id='l2h-180' xml:id='l2h-180' class="cfunction">PyImport_AddModule</tt></b>(</nobr></td><td>char *<var>name</var>)</td></tr></table></dt> |
| 149 | <dd> |
| 150 | <div class="refcount-info"> |
| 151 | <span class="label">Return value:</span> |
| 152 | <span class="value">Borrowed reference.</span> |
| 153 | </div> |
| 154 | Return the module object corresponding to a module name. The |
| 155 | <var>name</var> argument may be of the form <code>package.module</code>. |
| 156 | First check the modules dictionary if there's one there, and if not, |
| 157 | create a new one and insert it in the modules dictionary. |
| 158 | Return <tt class="constant">NULL</tt> with an exception set on failure. |
| 159 | <span class="note"><b class="label">Note:</b> |
| 160 | This function does not load or import the module; if the |
| 161 | module wasn't already loaded, you will get an empty module object. |
| 162 | Use <tt class="cfunction">PyImport_ImportModule()</tt> or one of its variants to |
| 163 | import a module. Package structures implied by a dotted name for |
| 164 | <var>name</var> are not created if not already present.</span> |
| 165 | </dd></dl> |
| 166 | |
| 167 | <P> |
| 168 | <dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline"><td><nobr>PyObject* <b><tt id='l2h-181' xml:id='l2h-181' class="cfunction">PyImport_ExecCodeModule</tt></b>(</nobr></td><td>char *<var>name</var>, PyObject *<var>co</var>)</td></tr></table></dt> |
| 169 | <dd> |
| 170 | <div class="refcount-info"> |
| 171 | <span class="label">Return value:</span> |
| 172 | <span class="value">New reference.</span> |
| 173 | </div> |
| 174 | Given a module name (possibly of the form <code>package.module</code>) and |
| 175 | a code object read from a Python bytecode file or obtained from the |
| 176 | built-in function <tt class="function">compile()</tt><a id='l2h-182' xml:id='l2h-182'></a>, load |
| 177 | the module. Return a new reference to the module object, or <tt class="constant">NULL</tt> |
| 178 | with an exception set if an error occurred. Before Python 2.4, the module |
| 179 | could still be created in error cases. Starting with Python 2.4, |
| 180 | <var>name</var> is removed from <code>sys.modules</code> in error cases, and even |
| 181 | if <var>name</var> was already in <code>sys.modules</code> on entry to |
| 182 | <tt class="cfunction">PyImport_ExecCodeModule()</tt>. Leaving incompletely initialized |
| 183 | modules in <code>sys.modules</code> is dangerous, as imports of such modules |
| 184 | have no way to know that the module object is an unknown (and probably |
| 185 | damaged with respect to the module author's intents) state. |
| 186 | |
| 187 | <P> |
| 188 | This function will reload the module if it was already imported. See |
| 189 | <tt class="cfunction">PyImport_ReloadModule()</tt> for the intended way to reload a |
| 190 | module. |
| 191 | |
| 192 | <P> |
| 193 | If <var>name</var> points to a dotted name of the |
| 194 | form <code>package.module</code>, any package structures not already |
| 195 | created will still not be created. |
| 196 | |
| 197 | <P> |
| 198 | |
| 199 | <span class="versionnote">Changed in version 2.4: |
| 200 | <var>name</var> is removed from <code>sys.modules</code> in error cases.</span> |
| 201 | |
| 202 | <P> |
| 203 | </dd></dl> |
| 204 | |
| 205 | <P> |
| 206 | <dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline"><td><nobr>long <b><tt id='l2h-183' xml:id='l2h-183' class="cfunction">PyImport_GetMagicNumber</tt></b>(</nobr></td><td>)</td></tr></table></dt> |
| 207 | <dd> |
| 208 | Return the magic number for Python bytecode files |
| 209 | (a.k.a. <span class="file">.pyc</span> and <span class="file">.pyo</span> files). The magic number should |
| 210 | be present in the first four bytes of the bytecode file, in |
| 211 | little-endian byte order. |
| 212 | </dd></dl> |
| 213 | |
| 214 | <P> |
| 215 | <dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline"><td><nobr>PyObject* <b><tt id='l2h-184' xml:id='l2h-184' class="cfunction">PyImport_GetModuleDict</tt></b>(</nobr></td><td>)</td></tr></table></dt> |
| 216 | <dd> |
| 217 | <div class="refcount-info"> |
| 218 | <span class="label">Return value:</span> |
| 219 | <span class="value">Borrowed reference.</span> |
| 220 | </div> |
| 221 | Return the dictionary used for the module administration |
| 222 | (a.k.a. <code>sys.modules</code>). Note that this is a per-interpreter |
| 223 | variable. |
| 224 | </dd></dl> |
| 225 | |
| 226 | <P> |
| 227 | <dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline"><td><nobr>void <b><tt id='l2h-185' xml:id='l2h-185' class="cfunction">_PyImport_Init</tt></b>(</nobr></td><td>)</td></tr></table></dt> |
| 228 | <dd> |
| 229 | Initialize the import mechanism. For internal use only. |
| 230 | </dd></dl> |
| 231 | |
| 232 | <P> |
| 233 | <dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline"><td><nobr>void <b><tt id='l2h-186' xml:id='l2h-186' class="cfunction">PyImport_Cleanup</tt></b>(</nobr></td><td>)</td></tr></table></dt> |
| 234 | <dd> |
| 235 | Empty the module table. For internal use only. |
| 236 | </dd></dl> |
| 237 | |
| 238 | <P> |
| 239 | <dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline"><td><nobr>void <b><tt id='l2h-187' xml:id='l2h-187' class="cfunction">_PyImport_Fini</tt></b>(</nobr></td><td>)</td></tr></table></dt> |
| 240 | <dd> |
| 241 | Finalize the import mechanism. For internal use only. |
| 242 | </dd></dl> |
| 243 | |
| 244 | <P> |
| 245 | <dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline"><td><nobr>PyObject* <b><tt id='l2h-188' xml:id='l2h-188' class="cfunction">_PyImport_FindExtension</tt></b>(</nobr></td><td>char *, char *)</td></tr></table></dt> |
| 246 | <dd> |
| 247 | <div class="refcount-info"> |
| 248 | <span class="label">Return value:</span> |
| 249 | <span class="value">Borrowed reference.</span> |
| 250 | </div> |
| 251 | For internal use only. |
| 252 | </dd></dl> |
| 253 | |
| 254 | <P> |
| 255 | <dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline"><td><nobr>PyObject* <b><tt id='l2h-189' xml:id='l2h-189' class="cfunction">_PyImport_FixupExtension</tt></b>(</nobr></td><td>char *, char *)</td></tr></table></dt> |
| 256 | <dd> |
| 257 | For internal use only. |
| 258 | </dd></dl> |
| 259 | |
| 260 | <P> |
| 261 | <dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline"><td><nobr>int <b><tt id='l2h-190' xml:id='l2h-190' class="cfunction">PyImport_ImportFrozenModule</tt></b>(</nobr></td><td>char *<var>name</var>)</td></tr></table></dt> |
| 262 | <dd> |
| 263 | Load a frozen module named <var>name</var>. Return <code>1</code> for success, |
| 264 | <code>0</code> if the module is not found, and <code>-1</code> with an exception |
| 265 | set if the initialization failed. To access the imported module on |
| 266 | a successful load, use <tt class="cfunction">PyImport_ImportModule()</tt>. (Note |
| 267 | the misnomer -- this function would reload the module if it was |
| 268 | already imported.) |
| 269 | </dd></dl> |
| 270 | |
| 271 | <P> |
| 272 | <dl><dt><b><tt class="ctype"><a id='l2h-191' xml:id='l2h-191'>struct _frozen</a></tt></b></dt> |
| 273 | <dd> |
| 274 | This is the structure type definition for frozen module descriptors, |
| 275 | as generated by the <b class="program">freeze</b><a id='l2h-199' xml:id='l2h-199'></a> utility |
| 276 | (see <span class="file">Tools/freeze/</span> in the Python source distribution). Its |
| 277 | definition, found in <span class="file">Include/import.h</span>, is: |
| 278 | |
| 279 | <P> |
| 280 | <div class="verbatim"><pre> |
| 281 | struct _frozen { |
| 282 | char *name; |
| 283 | unsigned char *code; |
| 284 | int size; |
| 285 | }; |
| 286 | </pre></div> |
| 287 | </dl> |
| 288 | |
| 289 | <P> |
| 290 | <dl><dt>struct _frozen* <b><tt id='l2h-192' xml:id='l2h-192' class="cdata">PyImport_FrozenModules</tt></b></dt> |
| 291 | <dd> |
| 292 | This pointer is initialized to point to an array of <tt class="ctype">struct |
| 293 | _frozen</tt> records, terminated by one whose members are all <tt class="constant">NULL</tt> or |
| 294 | zero. When a frozen module is imported, it is searched in this |
| 295 | table. Third-party code could play tricks with this to provide a |
| 296 | dynamically created collection of frozen modules. |
| 297 | </dd></dl> |
| 298 | |
| 299 | <P> |
| 300 | <dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline"><td><nobr>int <b><tt id='l2h-193' xml:id='l2h-193' class="cfunction">PyImport_AppendInittab</tt></b>(</nobr></td><td>char *<var>name</var>, |
| 301 | void (*initfunc)(void))</td></tr></table></dt> |
| 302 | <dd> |
| 303 | Add a single module to the existing table of built-in modules. This |
| 304 | is a convenience wrapper around |
| 305 | <tt class="cfunction">PyImport_ExtendInittab()</tt>, returning <code>-1</code> if the |
| 306 | table could not be extended. The new module can be imported by the |
| 307 | name <var>name</var>, and uses the function <var>initfunc</var> as the |
| 308 | initialization function called on the first attempted import. This |
| 309 | should be called before <tt class="cfunction">Py_Initialize()</tt>. |
| 310 | </dd></dl> |
| 311 | |
| 312 | <P> |
| 313 | <dl><dt><b><tt class="ctype"><a id='l2h-194' xml:id='l2h-194'>struct _inittab</a></tt></b></dt> |
| 314 | <dd> |
| 315 | Structure describing a single entry in the list of built-in |
| 316 | modules. Each of these structures gives the name and initialization |
| 317 | function for a module built into the interpreter. Programs which |
| 318 | embed Python may use an array of these structures in conjunction |
| 319 | with <tt class="cfunction">PyImport_ExtendInittab()</tt> to provide additional |
| 320 | built-in modules. The structure is defined in |
| 321 | <span class="file">Include/import.h</span> as: |
| 322 | |
| 323 | <P> |
| 324 | <div class="verbatim"><pre> |
| 325 | struct _inittab { |
| 326 | char *name; |
| 327 | void (*initfunc)(void); |
| 328 | }; |
| 329 | </pre></div> |
| 330 | </dl> |
| 331 | |
| 332 | <P> |
| 333 | <dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline"><td><nobr>int <b><tt id='l2h-195' xml:id='l2h-195' class="cfunction">PyImport_ExtendInittab</tt></b>(</nobr></td><td>struct _inittab *<var>newtab</var>)</td></tr></table></dt> |
| 334 | <dd> |
| 335 | Add a collection of modules to the table of built-in modules. The |
| 336 | <var>newtab</var> array must end with a sentinel entry which contains |
| 337 | <tt class="constant">NULL</tt> for the <tt class="member">name</tt> field; failure to provide the sentinel |
| 338 | value can result in a memory fault. Returns <code>0</code> on success or |
| 339 | <code>-1</code> if insufficient memory could be allocated to extend the |
| 340 | internal table. In the event of failure, no modules are added to |
| 341 | the internal table. This should be called before |
| 342 | <tt class="cfunction">Py_Initialize()</tt>. |
| 343 | </dd></dl> |
| 344 | |
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| 381 | <span class="release-info">Release 2.4.2, documentation updated on 28 September 2005.</span> |
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