# 导入模块

PyObject* `PyImport_ImportModule`(const char *name)
  Return value: New reference.

  这是下面 `PyImport_ImportModuleEx()` 的简化版接口，将 globals 和 locals 参数设为 `NULL` 并将 level 设为 0。 当 name 参数包含一个点号（即指定了一个包的子模块）时，fromlist 参数会被设为列表 `['*']` 这样返回值将为所指定的模块而不像在其他情况下那样为包含模块的最高层级包。 （不幸的是，这在 name 实际上是指定一个子包而非子模块时将有一个额外的副作用：在包的 `__all__` 变量中指定的子模块会被加载。） 返回一个对所导入模块的新引用，或是在导入失败时返回 `NULL` 并设置一个异常。 模块导入失败同模块不会留 在 `sys.modules` 中。

  该函数总是使用绝对路径导入。

PyObject* `PyImport_ImportModuleNoBlock`(const char *name)
  Return value: New reference.

  该函数是 `PyImport_ImportModule()` 的一个被弃用的别名。

  在 3.3 版更改: 在导入锁被另一线程掌控时此函数会立即失败。 但是从 Python 3.3 起，锁方案在大多数情况下都已切换为针对每个模块加锁，所以此函数的特殊行为已无必要。

PyObject* `PyImport_ImportModuleEx`(const char *name, PyObject *globals, PyObject *locals, PyObject *fromlist)
  Return value: New reference.

  导入一个模块。 请参阅内置 Python 函数 `__import__()` 获取完善的相关描述。

  返回值是一个对所导入模块或最高层级包的新引用，或是在导入失败时则为 `NULL` 并设置一个异常。 与 `__import__()` 类似，当请求一个包的子模块时返回值通常为该最高层级包，除非给出了一个非空的 fromlist。

  导入失败将移动不完整的模块对象，就像 `PyImport_ImportModule()` 那样。

PyObject* `PyImport_ImportModuleLevelObject`(PyObject *name, PyObject *globals, PyObject *locals, PyObject *fromlist, int level)
  Return value: New reference.

  Import a module. This is best described by referring to the built-in Python function `__import__()`, as the standard `__import__()` function calls this function directly.

  返回值是一个对所导入模块或最高层级包的新引用，或是在导入失败时则为 `NULL` 并设置一个异常。 与 `__import__()` 类似，当请求一个包的子模块时返回值通常为该最高层级包，除非给出了一个非空的 fromlist。

  3.3 新版功能.

PyObject* `PyImport_ImportModuleLevel`(const char *name, PyObject *globals, PyObject *locals, PyObject *fromlist, int level)
  Return value: New reference.

  Similar to `PyImport_ImportModuleLevelObject()`, but the name is a UTF-8 encoded string instead of a Unicode object.

  在 3.3 版更改: Negative values for level are no longer accepted.

PyObject* `PyImport_Import`(PyObject *name)
  Return value: New reference.

  This is a higher-level interface that calls the current "import hook function" (with an explicit level of 0, meaning absolute import). It invokes the `__import__()` function from the `__builtins__` of the current globals. This means that the import is done using whatever import hooks are installed in the current environment.

  该函数总是使用绝对路径导入。

PyObject* `PyImport_ReloadModule`(PyObject *m)
  Return value: New reference.

  Reload a module. Return a new reference to the reloaded module, or `NULL` with an exception set on failure (the module still exists in this case).

PyObject* `PyImport_AddModuleObject`(PyObject *name)
  Return value: Borrowed reference.

  Return the module object corresponding to a module name. The name argument may be of the form `package.module`. First check the modules dictionary if there's one there, and if not, create a new one and insert it in the modules dictionary. Return `NULL` with an exception set on failure.

  注解

  This function does not load or import the module; if the module wasn't already loaded, you will get an empty module object. Use `PyImport_ImportModule()` or one of its variants to import a module. Package structures implied by a dotted name for name are not created if not already present.

  3.3 新版功能.

PyObject* `PyImport_AddModule`(const char *name)
  Return value: Borrowed reference.

  Similar to `PyImport_AddModuleObject()`, but the name is a UTF-8 encoded string instead of a Unicode object.

PyObject* `PyImport_ExecCodeModule`(const char *name, PyObject *co)
  Return value: New reference.

  Given a module name (possibly of the form `package.module`) and a code object read from a Python bytecode file or obtained from the built-in function `compile()`, load the module. Return a new reference to the module object, or `NULL` with an exception set if an error occurred. name is removed from `sys.modules` in error cases, even if name was already in `sys.modules` on entry to `PyImport_ExecCodeModule()`. Leaving incompletely initialized modules in `sys.modules` is dangerous, as imports of such modules have no way to know that the module object is an unknown (and probably damaged with respect to the module author's intents) state.

  The module's `__spec__` and `__loader__` will be set, if not set already, with the appropriate values. The spec's loader will be set to the module's `__loader__` (if set) and to an instance of `SourceFileLoader` otherwise.

  The module's `__file__` attribute will be set to the code object's `co_filename`. If applicable, `__cached__` will also be set.

  This function will reload the module if it was already imported. See `PyImport_ReloadModule()` for the intended way to reload a module.

  If name points to a dotted name of the form `package.module`, any package structures not already created will still not be created.

  See also `PyImport_ExecCodeModuleEx()` and `PyImport_ExecCodeModuleWithPathnames()`.

PyObject* `PyImport_ExecCodeModuleEx`(const char *name, PyObject *co, const char *pathname)
  Return value: New reference.

  Like `PyImport_ExecCodeModule()`, but the `__file__` attribute of the module object is set to pathname if it is non-`NULL`.

  参见 `PyImport_ExecCodeModuleWithPathnames()`。

PyObject* `PyImport_ExecCodeModuleObject`(PyObject *name, PyObject *co, PyObject *pathname, PyObject *cpathname)
  Return value: New reference.

  Like `PyImport_ExecCodeModuleEx()`, but the `__cached__` attribute of the module object is set to cpathname if it is non-`NULL`. Of the three functions, this is the preferred one to use.

  3.3 新版功能.

PyObject* `PyImport_ExecCodeModuleWithPathnames`(const char *name, PyObject *co, const char *pathname, const char *cpathname)
  Return value: New reference.

  Like `PyImport_ExecCodeModuleObject()`, but name, pathname and cpathname are UTF-8 encoded strings. Attempts are also made to figure out what the value for pathname should be from cpathname if the former is set to `NULL`.

  3.2 新版功能.

  在 3.3 版更改: Uses `imp.source_from_cache()` in calculating the source path if only the bytecode path is provided.

long `PyImport_GetMagicNumber`()

  Return the magic number for Python bytecode files (a.k.a. `.pyc` file). The magic number should be present in the first four bytes of the bytecode file, in little-endian byte order. Returns `-1` on error.

  在 3.3 版更改: 失败时返回值 `-1`。

const char * `PyImport_GetMagicTag`()

  Return the magic tag string for PEP 3147 format Python bytecode file names. Keep in mind that the value at `sys.implementation.cache_tag` is authoritative and should be used instead of this function.

  3.2 新版功能.

PyObject* `PyImport_GetModuleDict`()
  Return value: Borrowed reference.

  Return the dictionary used for the module administration (a.k.a. `sys.modules`). Note that this is a per-interpreter variable.

PyObject* `PyImport_GetModule`(PyObject *name)
  Return value: New reference.

  Return the already imported module with the given name. If the module has not been imported yet then returns `NULL` but does not set an error. Returns `NULL` and sets an error if the lookup failed.

  3.7 新版功能.

PyObject* `PyImport_GetImporter`(PyObject *path)
  Return value: New reference.

  Return a finder object for a `sys.path`/`pkg.__path__` item path, possibly by fetching it from the `sys.path_importer_cache` dict. If it wasn't yet cached, traverse `sys.path_hooks` until a hook is found that can handle the path item. Return `None` if no hook could; this tells our caller that the path based finder could not find a finder for this path item. Cache the result in `sys.path_importer_cache`. Return a new reference to the finder object.

int `PyImport_ImportFrozenModuleObject`(PyObject *name)
  Return value: New reference.

  Load a frozen module named name. Return `1` for success, `0` if the module is not found, and `-1` with an exception set if the initialization failed. To access the imported module on a successful load, use `PyImport_ImportModule()`. (Note the misnomer --- this function would reload the module if it was already imported.)

  3.3 新版功能.

  在 3.4 版更改: The `__file__` attribute is no longer set on the module.

int `PyImport_ImportFrozenModule`(const char *name)

  Similar to `PyImport_ImportFrozenModuleObject()`, but the name is a UTF-8 encoded string instead of a Unicode object.

struct `_frozen`

  This is the structure type definition for frozen module descriptors, as generated by the freeze utility (see `Tools/freeze/` in the Python source distribution). Its definition, found in `Include/import.h`, is:

      struct _frozen {
          const char *name;
          const unsigned char *code;
          int size;
      };

const struct _frozen* `PyImport_FrozenModules`

  该指针被初始化为指向 `struct _frozen` 数组，以 `NULL` 或者 0 作为结束标记。当一个冻结模块被导入，首先要在这个表中搜索。第三方库可以以此来提供动态创建的冻结模块集合。

int `PyImport_AppendInittab`(const char *name, PyObject* (*initfunc)(void))

  Add a single module to the existing table of built-in modules. This is a convenience wrapper around `PyImport_ExtendInittab()`, returning `-1` if the table could not be extended. The new module can be imported by the name name, and uses the function initfunc as the initialization function called on the first attempted import. This should be called before `Py_Initialize()`.

struct `_inittab`

  Structure describing a single entry in the list of built-in modules. Each of these structures gives the name and initialization function for a module built into the interpreter. The name is an ASCII encoded string. Programs which embed Python may use an array of these structures in conjunction with `PyImport_ExtendInittab()` to provide additional built-in modules. The structure is defined in `Include/import.h` as:

      struct _inittab {
          const char *name;           /* ASCII encoded string */
          PyObject* (*initfunc)(void);
      };

int `PyImport_ExtendInittab`(struct _inittab *newtab)

  Add a collection of modules to the table of built-in modules. The newtab array must end with a sentinel entry which contains `NULL` for the `name` field; failure to provide the sentinel value can result in a memory fault. Returns `0` on success or `-1` if insufficient memory could be allocated to extend the internal table. In the event of failure, no modules are added to the internal table. This must be called before `Py_Initialize()`.

  如果 Python 要被多次初始化，则 `PyImport_AppendInittab()` 或 `PyImport_ExtendInittab()` 必须在每次 Python 初始化之前调用。