导入挂钩的 Ironpython 问题 subpackage/submodule

Question

我一直在努力解决我现在认为可能是 IronPython 中的错误的问题。如果有人能证实这个怀疑或纠正我的错误，我将不胜感激。

我面临的问题是在尝试使用 sys.meta_path 或 sys.path_hooks 应用导入挂钩时。在导入简单的模块和包时，IronPython 似乎正确地调用了我的钩子。如果我尝试导入一个子模块或包，例如 foo.bar，则会调用挂钩来导入 foo，但在尝试导入 bar 时不会调用挂钩。

我创建了以下代码来重现该问题。当运行在 CPython 中时，同样的代码不会遇到任何问题。

import imp
import sys

class ReflectiveLoader2(object):

def __init__(self):
    print "Init RL2"

def find_module(self, fullname, path=None):
    print "find_module_RL2 called with fullname %s and path %s" % (fullname, path)
    self.path = path
    return self

def load_module(self, fullname):
    print "load_module_RL2 called with fullname %s" % fullname

    mod = imp.new_module(fullname)
    mod.__name__ = fullname
    mod.__loader__ = self
    #Simulate a couple scenarios for imports
    #Simulate a method
    if fullname == "foo":
        print "its foo"
        mod.__filepath__ = r"C:\not\a\real\path\foo.py"
        source = "def fooFunction(thing):print thing*3"

    #Simulate another method
    elif fullname == "bar":
        print "its bar"
        mod.__filepath__ = r"C:\not\a\real\path\bar.py"
        source = "def barFunction(thing):print thing*4"

    #Simulate package
    elif fullname == "baz":
        print "its baz"
        mod.__filepath__ = r"C:\not\a\real\path\baz\__init__.py"
        mod.__path__ = r"C:\not\a\real\path\baz"
        source = "print 'initializing baz stuff here'"

    #Simulate subpackage
    elif fullname == "baz.bat":
        print "its baz.bat"
        mod.__filepath__ = r"C:\not\a\real\path\baz\bat.py"
        mod.__path__ = r"C:\not\a\real\path\baz"
            source = "def Batfunc():print 'in baz.bat sub package'"

    #catchall
    else:
        print "Not foo, bar or baz its %s" % fullname
        source = ""

    exec source in mod.__dict__
    return mod


sys.meta_path = [ReflectiveLoader2()]

import foo
foo.fooFunction("ABC")

import bar
bar.barFunction("DEF")

import baz.bat
baz.bat.Batfunc()

这是使用 IronPython 和 CPython 的上述代码的输出。我在两个独立的系统上有运行这段代码，以防其中一个系统安装错误

  C:\Users\Administrator\project>"C:\Program Files (x86)\IronPython 2.7\ipy.exe" ReflectiveLoader2.py
    Init RL2
    find_module_RL2 called with fullname foo and path None
    load_module_RL2 called with fullname foo
    its foo
    ABCABCABC
    find_module_RL2 called with fullname bar and path None
    load_module_RL2 called with fullname bar
    its bar
    DEFDEFDEFDEF
    find_module_RL2 called with fullname baz and path None
    load_module_RL2 called with fullname baz
    its baz
    initializing baz stuff here

    Traceback (most recent call last):
        File "ReflectiveLoader2.py", line 63, in <module>
        ImportError: No module named bat

 C:\Users\Administrator\project>C:\Python27\python.exe ReflectiveLoader2.py
    Init RL2
    find_module_RL2 called with fullname foo and path None
    load_module_RL2 called with fullname foo
    its foo
    ABCABCABC
    find_module_RL2 called with fullname bar and path None
    load_module_RL2 called with fullname bar
    its bar
    DEFDEFDEFDEF
    find_module_RL2 called with fullname baz and path None
    load_module_RL2 called with fullname baz
    its baz
    initializing baz stuff here
    find_module_RL2 called with fullname baz.bat and path C:\not\a\real\path\baz
    load_module_RL2 called with fullname baz.bat
    its baz.bat
    in baz.bat sub package

编辑：我忘了说我试过研究其他人是否有这个问题，我能找到的最接近的是 post

https://mail.python.org/pipermail/ironpython-users/2012-April/015879.html

据我所知，没有采取任何措施来解决所报告的问题

Answer 1

经过一些额外的故障排除后，我认为这主要是操作员错误。看起来 CPython 在模块的路径属性方面稍微宽容一些。如果把上面的代码改成

mod.__path__ = r"C:\not\a\real\path\baz"

看起来像

mod.__path__ = [r"C:\not\a\real\path\baz",]

一切正常。

如果有人有足够的动力为 IronPython 创建类似的类型检查，我在 IronPython 源文件 IronPython\Runtime\Importer.cs 的第 151 和 120 行附近发现了不检查列表类型的代码，如下所示

object path;
List listPath;
    if (scope.__dict__._storage.TryGetPath(out path) && (listPath = path as List) != null) {
        return ImportNestedModule(context, scope, new [] {name}, 0, listPath);
                }

如果将 __path__ 设置为字符串（代替预期的列表），则转换为列表会失败，并且永远不会调用 ImportNestedModule。

CPython 和 IronPython 之间的不一致问题已经解决 https://github.com/IronLanguages/main/issues/1202

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