From 0c1c3fae1041e5cbae88aa8545820e2f22755764 Mon Sep 17 00:00:00 2001
From: brettlangdon <me@brett.is>
Date: Sat, 25 Aug 2018 12:17:50 -0400
Subject: [PATCH] initial prototype

---
 virtualmod.py | 96 +++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 96 insertions(+)
 create mode 100644 virtualmod.py

diff --git a/virtualmod.py b/virtualmod.py
new file mode 100644
index 0000000..19b1619
--- /dev/null
+++ b/virtualmod.py
@@ -0,0 +1,96 @@
+import importlib
+from importlib.abc import Loader, MetaPathFinder
+import sys
+
+registry = dict()
+
+module_cls = type(sys)
+spec_cls = type(sys.__spec__)
+
+
+class VirtualModule:
+    __slots__ = ['name', 'module', 'spec']
+
+    def __init__(self, name):
+        self.name = name
+        self.module = module_cls(name)
+        self.spec = spec_cls(name=name, loader=VirtualModuleLoader)
+        setattr(self.module, '__spec__', self.spec)
+
+    def set_attribute(self, name, value):
+        setattr(self.module, name, value)
+
+    def delete_attribute(self, name):
+        delattr(self.module, name)
+
+
+def create_module(name):
+    module = VirtualModule(name)
+    registry[name] = module
+    return module
+
+
+def copy_module(module):
+    name = module.__name__
+    if hasattr(module, '__spec__'):
+        name = module.__spec__.name
+
+    virt_mod = VirtualModule(name)
+    for key, value in module.__dict__.items():
+        if key in ('__spec__', '__name__', '__loader__', '__package__'):
+            continue
+        virt_mod.set_attribute(key, value)
+
+    registry[name] = virt_mod
+    importlib.reload(module)
+    return virt_mod
+
+
+def as_module(cls_or_name):
+    if isinstance(cls_or_name, str):
+        cls = None
+        name = cls_or_name
+    elif isinstance(cls_or_name, type):
+        cls = cls_or_name
+        name = getattr(cls, '__module_name__', cls.__name__)
+    else:
+        raise ValueError('Expected as_module to be passed a string or a class type')
+
+    def wrapper(cls):
+        module = create_module(name)
+
+        for key, value in cls.__dict__.items():
+            if key.startswith('__') and key.endswith('__'):
+                continue
+
+            module.set_attribute(key, value)
+        return module
+
+    if cls is None:
+        return wrapper
+    return wrapper(cls)
+
+
+class VirtualModuleLoader(Loader):
+    def create_module(spec):
+        if spec.name not in registry:
+            return None
+
+        return registry[spec.name].module
+
+    def exec_module(module):
+        module_name = module.__name__
+        if hasattr(module, '__spec__'):
+            module_name = module.__spec__.name
+
+        sys.modules[module_name] = module
+
+
+class VirtualModuleFinder(MetaPathFinder):
+    def find_spec(fullname, path, target=None):
+        if fullname in registry:
+            return registry[fullname].spec
+        return None
+
+
+sys.meta_path.insert(0, VirtualModuleFinder)