Provision for autoloading from outside core.

Author: rocky

mathics/core/definitions.py

@@ -41,6 +41,27 @@ def valuesname(name) -> str:
         return name[7:-6].lower()
 
 
+def autoload_file(defs, root_dir_path: str, autoload_dir):
+    from mathics.core.evaluation import Evaluation
+
+    # Load symbols from the autoload folder
+    for root, dirs, files in os.walk(os.path.join(root_dir_path, autoload_dir)):
+        for path in [os.path.join(root, f) for f in files if f.endswith(".m")]:
+            Expression("Get", String(path)).evaluate(Evaluation(defs))
+
+    # Move any user definitions created by autoloaded files to
+    # builtins, and clear out the user definitions list. This
+    # means that any autoloaded definitions become shared
+    # between users and no longer disappear after a Quit[].
+    #
+    # Autoloads that accidentally define a name in Global`
+    # could cause confusion, so check for this.
+    #
+    for name in defs.user:
+        if name.startswith("Global`"):
+            raise ValueError("autoload defined %s." % name)
+
+
 class PyMathicsLoadException(Exception):
     def __init__(self, module):
         self.name = module + " is not a valid pymathics module"
@@ -78,18 +99,17 @@ def __init__(
                 contribute(self)
                 for module in extension_modules:
                     try:
-                        loaded_module = self.load_pymathics_module(
-                            module, remove_on_quit=False
-                        )
-                    except PyMathicsLoadException as e:
+                        self.load_pymathics_module(module, remove_on_quit=False)
+                    except PyMathicsLoadException:
                         raise
-                    except ImportError as e:
+                    except ImportError:
                         raise
 
                 if builtin_filename is not None:
                     builtin_file = open(builtin_filename, "wb")
                     pickle.dump(self.builtin, builtin_file, -1)
 
+            autoload_file(self, ROOT_DIR, "autoload")
             # Load symbols from the autoload folder
             for root, dirs, files in os.walk(os.path.join(ROOT_DIR, "autoload")):
                 for path in [os.path.join(root, f) for f in files if f.endswith(".m")]:
@@ -106,6 +126,7 @@ def __init__(
             for name in self.user:
                 if name.startswith("Global`"):
                     raise ValueError("autoload defined %s." % name)
+
             self.builtin.update(self.user)
             self.user = {}
             self.clear_cache()
@@ -475,7 +496,7 @@ def get_definition(self, name, only_if_exists=False) -> "Definition":
             self.lookup_cache[original_name] = name
         elif not only_if_exists:
             definition = Definition(name=name)
-            if name[-1] != '`':
+            if name[-1] != "`":
                 self.user[name] = definition
 
         return definition