suffixes = importlib.machinery.SOURCE_SUFFIXES
loader = importlib.machinery.SourceFileLoader
lazy_loader = importlib.util.LazyLoader.factory(loader)
- finder = importlib.machinery.FileFinder(path, [(lazy_loader, suffixes)])
+ finder = importlib.machinery.FileFinder(path, (lazy_loader, suffixes))
+
+.. _importlib-examples:
+
+Examples
+--------
+
+To programmatically import a module, use :func:`importlib.import_module`.
+::
+
+ import importlib
+
+ itertools = importlib.import_module('itertools')
+
+If you need to find out if a module can be imported without actually doing the
+import, then you should use :func:`importlib.util.find_spec`.
+::
+
+ import importlib.util
+ import sys
+
+ # For illustrative purposes.
+ name = 'itertools'
+
+ spec = importlib.util.find_spec(name)
+ if spec is None:
+ print("can't find the itertools module")
+ else:
+ # If you chose to perform the actual import.
+ module = importlib.util.module_from_spec(spec)
+ spec.loader.exec_module(module)
+ # Adding the module to sys.modules is optional.
+ sys.modules[name] = module
+
+To import a Python source file directly, use the following recipe
+(Python 3.4 and newer only)::
+
+ import importlib.util
+ import sys
+
+ # For illustrative purposes.
+ import tokenize
+ file_path = tokenize.__file__
+ module_name = tokenize.__name__
+
+ spec = importlib.util.spec_from_file_location(module_name, file_path)
+ module = importlib.util.module_from_spec(spec)
+ spec.loader.exec_module(module)
+ # Optional; only necessary if you want to be able to import the module
+ # by name later.
+ sys.modules[module_name] = module
+
+Import itself is implemented in Python code, making it possible to
+expose most of the import machinery through importlib. The following
+helps illustrate the various APIs that importlib exposes by providing an
+approximate implementation of
+:func:`importlib.import_module` (Python 3.4 and newer for importlib usage,
+Python 3.6 and newer for other parts of the code).
+::
+
+ import importlib.util
+ import sys
+
+ def import_module(name, package=None):
+ """An approximate implementation of import."""
+ absolute_name = importlib.util.resolve_name(name, package)
+ try:
+ return sys.modules[absolute_name]
+ except KeyError:
+ pass
+
+ path = None
+ if '.' in absolute_name:
+ parent_name, _, child_name = absolute_name.rpartition('.')
+ parent_module = import_module(parent_name)
+ path = parent_module.spec.submodule_search_locations
+ for finder in sys.meta_path:
+ spec = finder.find_spec(absolute_name, path)
+ if spec is not None:
+ break
+ else:
+ raise ImportError(f'No module named {absolute_name!r}')
+ module = spec.loader.create_module(spec)
+ spec.loader.exec_module(module)
+ sys.modules[absolute_name] = module
+ if path is not None:
+ setattr(parent_module, child_name, module)
+ return module