cpython/Lib/importlib/__init__.py

52 lines
1.7 KiB
Python

"""Backport of importlib.import_module from 3.x."""
# While not critical (and in no way guaranteed!), it would be nice to keep this
# code compatible with Python 2.3.
import sys
def _resolve_name(name, package, level):
"""Return the absolute name of the module to be imported."""
level -= 1
try:
if package.count('.') < level:
raise ValueError("attempted relative import beyond top-level "
"package")
except AttributeError:
raise ValueError("'package' not set to a string")
try:
# rpartition is more "correct" and rfind is just as easy to use, but
# neither are in Python 2.3.
dot_rindex = package.rindex('.', level)
base = package[:dot_rindex]
except ValueError:
base = package
if name:
return "%s.%s" % (base, name)
else:
return base
def import_module(name, package=None):
"""Import a module.
The 'package' argument is required when performing a relative import. It
specifies the package to use as the anchor point from which to resolve the
relative import to an absolute import.
"""
if name.startswith('.'):
if not package:
raise TypeError("relative imports require the 'package' argument")
level = 0
for character in name:
if character != '.':
break
level += 1
name = _resolve_name(name[level:], package, level)
# Try to import specifying the level to be as accurate as possible, but
# realize that keyword arguments are not found in Python 2.3.
try:
__import__(name, level=0)
except TypeError:
__import__(name)
return sys.modules[name]