Support using variables in base config directly as normal variables.

mmcv/utils/config.py

@@ -5,13 +5,11 @@
 import os.path as osp
 import platform
 import shutil
-import sys
 import tempfile
 import uuid
 import warnings
 from argparse import Action, ArgumentParser
 from collections import abc
-from importlib import import_module
 
 from addict import Dict
 from yapf.yapflib.yapf_api import FormatCode
@@ -175,9 +173,35 @@ def _substitute_base_vars(cfg, base_var_dict, base_cfg):
 
         return cfg
 
+    @staticmethod
+    def parse_base_files(filename):
+        if filename.endswith('.py'):
+            Config._validate_py_syntax(filename)
+            with open(filename) as f:
+                codes = ast.parse(f.read()).body
+
+                def is_base_line(c):
+                    return (isinstance(c, ast.Assign)
+                            and c.targets[0].id == BASE_KEY)
+
+                base_code = next((c for c in codes if is_base_line(c)), None)
+                if base_code is not None:
+                    base_code = ast.Expression(body=base_code.value)
+                    base_files = eval(compile(base_code, '', mode='eval'))
+                else:
+                    base_files = []
+        elif filename.endswith(('.yml', '.yaml', '.json')):
+            import mmcv
+            cfg_dict = mmcv.load(filename)
+            base_files = cfg_dict.get(BASE_KEY, [])
+        base_files = base_files if isinstance(base_files,
+                                              list) else [base_files]
+        return base_files
+
     @staticmethod
     def _file2dict(filename, use_predefined_variables=True):
         filename = osp.abspath(osp.expanduser(filename))
+        cfg_dir = osp.dirname(filename)
         check_file_exist(filename)
         fileExtname = osp.splitext(filename)[1]
         if fileExtname not in ['.py', '.json', '.yaml', '.yml']:
@@ -188,7 +212,6 @@ def _file2dict(filename, use_predefined_variables=True):
                 dir=temp_config_dir, suffix=fileExtname)
             if platform.system() == 'Windows':
                 temp_config_file.close()
-            temp_config_name = osp.basename(temp_config_file.name)
             # Substitute predefined variables
             if use_predefined_variables:
                 Config._substitute_predefined_vars(filename,
@@ -199,19 +222,27 @@ def _file2dict(filename, use_predefined_variables=True):
             base_var_dict = Config._pre_substitute_base_vars(
                 temp_config_file.name, temp_config_file.name)
 
+            # Handle base files
+            #  base_filename = cfg_dict.pop(BASE_KEY)
+            #  base_filename = base_filename if isinstance(
+            #      base_filename, list) else [base_filename]
+            base_cfg_dict = dict()
+            cfg_text_list = list()
+            for f in Config.parse_base_files(temp_config_file.name):
+                _cfg_dict, _cfg_text = Config._file2dict(osp.join(cfg_dir, f))
+                cfg_text_list.append(_cfg_text)
+                duplicate_keys = base_cfg_dict.keys() & _cfg_dict.keys()
+                if len(duplicate_keys) > 0:
+                    raise KeyError('Duplicate key is not allowed among bases. '
+                                   f'Duplicate keys: {duplicate_keys}')
+                base_cfg_dict.update(_cfg_dict)
+
             if filename.endswith('.py'):
-                temp_module_name = osp.splitext(temp_config_name)[0]
-                sys.path.insert(0, temp_config_dir)
-                Config._validate_py_syntax(filename)
-                mod = import_module(temp_module_name)
-                sys.path.pop(0)
-                cfg_dict = {
-                    name: value
-                    for name, value in mod.__dict__.items()
-                    if not name.startswith('__')
-                }
-                # delete imported module
-                del sys.modules[temp_module_name]
+                cfg_dict = {}
+                with open(temp_config_file.name, 'r') as f:
+                    content = f.read()
+                codeobj = compile(content, '', mode='exec')
+                eval(codeobj, base_cfg_dict, cfg_dict)
             elif filename.endswith(('.yml', '.yaml', '.json')):
                 import mmcv
                 cfg_dict = mmcv.load(temp_config_file.name)
@@ -236,37 +267,20 @@ def _file2dict(filename, use_predefined_variables=True):
             # Setting encoding explicitly to resolve coding issue on windows
             cfg_text += f.read()
 
-        if BASE_KEY in cfg_dict:
-            cfg_dir = osp.dirname(filename)
-            base_filename = cfg_dict.pop(BASE_KEY)
-            base_filename = base_filename if isinstance(
-                base_filename, list) else [base_filename]
-
-            cfg_dict_list = list()
-            cfg_text_list = list()
-            for f in base_filename:
-                _cfg_dict, _cfg_text = Config._file2dict(osp.join(cfg_dir, f))
-                cfg_dict_list.append(_cfg_dict)
-                cfg_text_list.append(_cfg_text)
-
-            base_cfg_dict = dict()
-            for c in cfg_dict_list:
-                duplicate_keys = base_cfg_dict.keys() & c.keys()
-                if len(duplicate_keys) > 0:
-                    raise KeyError('Duplicate key is not allowed among bases. '
-                                   f'Duplicate keys: {duplicate_keys}')
-                base_cfg_dict.update(c)
-
-            # Substitute base variables from strings to their actual values
-            cfg_dict = Config._substitute_base_vars(cfg_dict, base_var_dict,
-                                                    base_cfg_dict)
+        # Substitute base variables from strings to their actual values
+        cfg_dict = Config._substitute_base_vars(cfg_dict, base_var_dict,
+                                                base_cfg_dict)
+        cfg_dict.pop(BASE_KEY, None)
 
-            base_cfg_dict = Config._merge_a_into_b(cfg_dict, base_cfg_dict)
-            cfg_dict = base_cfg_dict
+        cfg_dict = Config._merge_a_into_b(cfg_dict, base_cfg_dict)
+        cfg_dict = {
+            k: v
+            for k, v in cfg_dict.items() if not k.startswith('__')
+        }
 
-            # merge cfg_text
-            cfg_text_list.append(cfg_text)
-            cfg_text = '\n'.join(cfg_text_list)
+        # merge cfg_text
+        cfg_text_list.append(cfg_text)
+        cfg_text = '\n'.join(cfg_text_list)
 
         return cfg_dict, cfg_text