收集/自写的一些实用的函数

 

 

通过path获取module

from importlib import import_module
def load_object(path):
    """Load an object given its absolute object path, and return it.

    object can be a class, function, variable or an instance.
    path ie: 'scrapy.downloadermiddlewares.redirect.RedirectMiddleware'
    """

    try:
        dot = path.rindex('.')
    except ValueError:
        raise ValueError("Error loading object '%s': not a full path" % path)

    module, name = path[:dot], path[dot+1:]
    # module, _, name = path.rpartition(".")
    # if not all([module,name]):raise ValueError("Error loading object '%s': not a full path" % path)
    mod = import_module(module)


    try:
        obj = getattr(mod, name)
    except AttributeError:
        raise NameError("Module '%s' doesn't define any object named '%s'" % (module, name))

    return obj

 

在看ing，先记录

from importlib import import_module
import sys
from functools import singledispatch as simplegeneric
from collections import namedtuple

ModuleInfo = namedtuple('ModuleInfo', 'module_finder name ispkg')
ModuleInfo.__doc__ = 'A namedtuple with minimal info about a module.'

@simplegeneric
def iter_importer_modules(importer, prefix=''):
    if not hasattr(importer, 'iter_modules'):
        return []
    return importer.iter_modules(prefix)

def get_importer(path_item):
    """Retrieve a finder for the given path item

    The returned finder is cached in sys.path_importer_cache
    if it was newly created by a path hook.

    The cache (or part of it) can be cleared manually if a
    rescan of sys.path_hooks is necessary.
    """
    try:
        importer = sys.path_importer_cache[path_item]
    except KeyError:
        for path_hook in sys.path_hooks:
            try:
                importer = path_hook(path_item)
                sys.path_importer_cache.setdefault(path_item, importer)
                break
            except ImportError:
                pass
        else:
            importer = None
    return importer

def iter_importers(fullname=""):
    """Yield finders for the given module name

    If fullname contains a '.', the finders will be for the package
    containing fullname, otherwise they will be all registered top level
    finders (i.e. those on both sys.meta_path and sys.path_hooks).

    If the named module is in a package, that package is imported as a side
    effect of invoking this function.

    If no module name is specified, all top level finders are produced.
    """
    if fullname.startswith('.'):
        msg = "Relative module name {!r} not supported".format(fullname)
        raise ImportError(msg)
    if '.' in fullname:
        # Get the containing package's __path__
        pkg_name = fullname.rpartition(".")[0]
        pkg = import_module(pkg_name)
        path = getattr(pkg, '__path__', None)
        if path is None:
            return
    else:
        yield from sys.meta_path
        path = sys.path
    for item in path:
        yield get_importer(item)


def iter_modules(path=None, prefix=''):
    """Yields ModuleInfo for all submodules on path,
    or, if path is None, all top-level modules on sys.path.

    'path' should be either None or a list of paths to look for
    modules in.

    'prefix' is a string to output on the front of every module name
    on output.
    """
    if path is None:
        importers = iter_importers()
    else:
        importers = map(get_importer, path)

    yielded = {}
    for i in importers:
        for name, ispkg in iter_importer_modules(i, prefix):
            if name not in yielded:
                yielded[name] = 1
                yield ModuleInfo(i, name, ispkg)


def walk_modules(path):
    """Loads a module and all its submodules from the given module path and
    returns them. If *any* module throws an exception while importing, that
    exception is thrown back.

    For example: walk_modules('scrapy.utils')
    """

    mods = []
    mod = import_module(path)
    mods.append(mod)
    if hasattr(mod, '__path__'):
        for _, subpath, ispkg in iter_modules(mod.__path__):
            fullpath = path + '.' + subpath
            if ispkg:
                mods += walk_modules(fullpath)
            else:
                submod = import_module(fullpath)
                mods.append(submod)
    return mods