在运行时导入包模块（Python配方）

http://code.activestate.com/recipes/223972/

###################
##                #
## classloader.py #
##                #
###################

import sys, types

def _get_mod(modulePath):
    try:
        aMod = sys.modules[modulePath]
        if not isinstance(aMod, types.ModuleType):
            raise KeyError
    except KeyError:
        # The last [''] is very important!
        aMod = __import__(modulePath, globals(), locals(), [''])
        sys.modules[modulePath] = aMod
    return aMod

def _get_func(fullFuncName):
    """Retrieve a function object from a full dotted-package name."""

    # Parse out the path, module, and function
    lastDot = fullFuncName.rfind(u".")
    funcName = fullFuncName[lastDot + 1:]
    modPath = fullFuncName[:lastDot]

    aMod = _get_mod(modPath)
    aFunc = getattr(aMod, funcName)

    # Assert that the function is a *callable* attribute.
    assert callable(aFunc), u"%s is not callable." % fullFuncName

    # Return a reference to the function itself,
    # not the results of the function.
    return aFunc

def _get_class(fullClassName, parentClass=None):
    """Load a module and retrieve a class (NOT an instance).

    If the parentClass is supplied, className must be of parentClass
    or a subclass of parentClass (or None is returned).
    """
    aClass = _get_func(fullClassName)

    # Assert that the class is a subclass of parentClass.
    if parentClass is not None:
        if not issubclass(aClass, parentClass):
            raise TypeError(u"%s is not a subclass of %s" %
                            (fullClassName, parentClass))

    # Return a reference to the class itself, not an instantiated object.
    return aClass


######################
##       Usage      ##
######################

class StorageManager: pass
class StorageManagerMySQL(StorageManager): pass

def storage_object(aFullClassName, allOptions={}):
    aStoreClass = _get_class(aFullClassName, StorageManager)
    return aStoreClass(allOptions)

这个答案是对Sebastian Rittau对评论的回答的补充：“但是如果你没有模块名怎么办？”这是一种快速而肮脏的方法，可以将可能的Python模块名指定为文件名——它只是沿着树向上移动，直到找到一个没有__init__.py文件的目录，然后将其转换回文件名。对于Python 3.4+（使用pathlib），这是有意义的，因为Python 2可以使用“imp”或其他方式进行相对导入：

import pathlib

def likely_python_module(filename):
    '''
    Given a filename or Path, return the "likely" python module name.  That is, iterate
    the parent directories until it doesn't contain an __init__.py file.

    :rtype: str
    '''
    p = pathlib.Path(filename).resolve()
    paths = []
    if p.name != '__init__.py':
        paths.append(p.stem)
    while True:
        p = p.parent
        if not p:
            break
        if not p.is_dir():
            break

        inits = [f for f in p.iterdir() if f.name == '__init__.py']
        if not inits:
            break

        paths.append(p.stem)

    return '.'.join(reversed(paths))

当然有改进的可能性，可选的__init__.py文件可能需要进行其他更改，但如果您通常有__init__.pry，这就有了窍门。

一种非常简单的方法：假设您希望导入具有相对路径../..的文件/MyLibs/pyfunc.py

libPath = '../../MyLibs'
import sys
if not libPath in sys.path: sys.path.append(libPath)
import pyfunc as pf

但如果你在没有守卫的情况下成功，你最终会走上一条很长的路。

您可以使用pydoc中的importfile

from pydoc import importfile
module = importfile('/full/path/to/module/module.py')
name = module.myclass() # myclass is a class inside your python file

听起来您不想专门导入配置文件（这会带来很多副作用和额外的复杂性）。您只需要运行它，并能够访问生成的命名空间。标准库以runpy.run_path的形式专门提供了一个API：

from runpy import run_path
settings = run_path("/path/to/file.py")

该接口在Python 2.7和Python 3.2+中可用。

我认为，最好的方法是从官方文件（29.1。imp-访问导入内部构件）：

import imp
import sys

def __import__(name, globals=None, locals=None, fromlist=None):
    # Fast path: see if the module has already been imported.
    try:
        return sys.modules[name]
    except KeyError:
        pass

    # If any of the following calls raises an exception,
    # there's a problem we can't handle -- let the caller handle it.

    fp, pathname, description = imp.find_module(name)

    try:
        return imp.load_module(name, fp, pathname, description)
    finally:
        # Since we may exit via an exception, close fp explicitly.
        if fp:
            fp.close()