Make it possible to inject global state during import

k4FWCore/python/k4FWCore/utils.py

@@ -19,31 +19,50 @@
 #
 import os
 from io import TextIOWrapper
-from typing import Union, Optional
+from typing import Union, Optional, Dict, Any
 import importlib.util
 import importlib.abc
-from importlib.machinery import SourceFileLoader, ModuleSpec
+from importlib.machinery import SourceFileLoader
 
 
-def import_from(filename: os.PathLike, module_name: Optional[str] = None) -> ModuleSpec:
-    """Import a module by filename optionally giving it a module name
+def import_from(
+    filename: os.PathLike,
+    module_name: Optional[str] = None,
+    global_vars: Optional[Dict[str, Any]] = None,
+) -> Any:
+    """Dynamically imports a module from the specified file path.
 
-    The module name is what will be visible in error messages, e.g. when trying
-    to get an attribute from the imported module
+    This function imports a module from a given filename, with the option to
+    specify the module's name and inject global variables into the module before
+    it is returned. If `module_name` is not provided, the filename is used as
+    the module name after replacing '.' with '_'. Global variables can be passed
+    as a dictionary to `global_vars`, which will be injected into the module's
+    namespace.
 
     Args:
-        filename: file to load
-        module_name: name of the module that should be used internally. If not
-            provided this will be computed from the filename
+        filename (str): The path to the file from which to import the module.
+        module_name (Optional[str]): The name to assign to the module. Defaults
+                                     to None, in which case the filename is used
+                                     as the module name.
+        global_vars (Optional[Dict[str, Any]]): A dictionary of global variables
+                                                to inject into the module's
+                                                namespace. Defaults to None.
+
+    Returns:
+        Any: The imported module with the specified modifications.
+
+    Raises:
+        FileNotFoundError: If the specified file does not exist.
+        ImportError: If there is an error during the import process.
 
-    Return:
-        The module imported from the provided file
     """
     filename = os.path.abspath(filename)
     module_name = module_name or os.path.basename(filename).replace(".", "_")
     loader = SourceFileLoader(module_name, filename)
     spec = importlib.util.spec_from_loader(loader.name, loader)
     module = importlib.util.module_from_spec(spec)
+    if global_vars:
+        module.__dict__.update(global_vars)
     loader.exec_module(module)
     return module