From: Brett Cannon <brett@python.org>
Date: Fri, 22 Jan 2016 22:05:41 +0000 (-0800)
Subject: Merge from 3.5
X-Git-Tag: v3.6.0a1~710
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=52c854a83819f1e5ec4aa907cdcc875b02a7ea07;p=python

Merge from 3.5
---

52c854a83819f1e5ec4aa907cdcc875b02a7ea07
diff --cc Doc/library/importlib.rst
index 45766a7b3f,4c8cc04224..9d5804e7ed
--- a/Doc/library/importlib.rst
+++ b/Doc/library/importlib.rst
@@@ -1306,91 -1298,4 +1306,91 @@@ an :term:`importer`
          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