从内存中的 zipfile 加载纯 Python 模块

Question

从开始，我做到了：

import os
import types
import zipfile
import sys
import io

class ZipImporter(object):
    def __init__(self, zip_file):
        self.zfile = zip_file
        self._paths = [x.filename for x in self.zfile.filelist]
        
    def _mod_to_paths(self, fullname):
        # get the python module name
        py_filename = fullname.replace(".", os.sep) + ".py"
        # get the filename if it is a package/subpackage
        py_package = fullname.replace(".", os.sep) + "/__init__.py"
        print(py_package)
        if py_filename in self._paths:
            return py_filename
        elif py_package in self._paths:
            return py_package
        else:
            return None

    def find_module(self, fullname, path):
        if self._mod_to_paths(fullname) is not None:
            return self
        return None

    def load_module(self, fullname):
        filename = self._mod_to_paths(fullname)
        if not filename in self._paths:
            raise ImportError(fullname)
        new_module = types.ModuleType(fullname)
        new_module.__name__=fullname
        print(fullname)
        exec(self.zfile.open(filename, 'r').read(),new_module.__dict__)
        new_module.__file__ = filename
        new_module.__loader__ = self
        if filename.endswith("__init__.py"):
            new_module.__path__ = [] 
            new_module.__package__ = fullname
        else:
            new_module.__package__ = fullname.rpartition('.')[0]
        sys.modules[fullname]=new_module
        return new_module

module_zip=zipfile.ZipFile(io.BytesIO(),"w")
for key in module_dict:
    module_zip.writestr(key,module_dict[key])
sys.meta_path.append(ZipImporter(module_zip))

import pyparsing

使用pyparsing的源代码作为测试。但是，它因 ImportError: attempted relative import with no known parent package 而失败。即使我将所有相对导入替换为绝对导入，它也会因 RecursionError: maximum recursion depth exceeded while calling a Python object 而失败，因为它会尝试重复导入 pyparsing。关于 Python 的导入系统的工作方式，有什么我不了解的基本知识吗？

Answer 1

我找到了答案 --- PEP 302 说：

Note that the module object must be in sys.modules before the loader executes the module code. This is crucial because the module code may (directly or indirectly) import itself; adding it to sys.modules beforehand prevents unbounded recursion in the worst case and multiple loading in the best.

从内存中的 zipfile 加载纯 Python 模块

Load pure Python module from in-memory zipfile

python-3.x

sys

python-zipfile

python-importlib