refine scope_guard, test=document_fix, test=develop (#20240)

paddle/fluid/API.spec

@@ -34,7 +34,7 @@ paddle.fluid.Executor.infer_from_dataset (ArgSpec(args=['self', 'program', 'data
 paddle.fluid.Executor.run (ArgSpec(args=['self', 'program', 'feed', 'fetch_list', 'feed_var_name', 'fetch_var_name', 'scope', 'return_numpy', 'use_program_cache'], varargs=None, keywords=None, defaults=(None, None, None, 'feed', 'fetch', None, True, False)), ('document', '4cfcd9c15b766a51b584cc46d38f1ad8'))
 paddle.fluid.Executor.train_from_dataset (ArgSpec(args=['self', 'program', 'dataset', 'scope', 'thread', 'debug', 'fetch_list', 'fetch_info', 'print_period', 'fetch_handler'], varargs=None, keywords=None, defaults=(None, None, None, 0, False, None, None, 100, None)), ('document', '73024c79f46b4f14f1060edeaa4919c8'))
 paddle.fluid.global_scope (ArgSpec(args=[], varargs=None, keywords=None, defaults=None), ('document', 'f65788d9ead293ada47551339df12203'))
-paddle.fluid.scope_guard (ArgSpec(args=['scope'], varargs=None, keywords=None, defaults=None), ('document', 'e6c073ed237001aaba7bff976b62b122'))
+paddle.fluid.scope_guard (ArgSpec(args=['scope'], varargs=None, keywords=None, defaults=None), ('document', '02fcfc1eda07c03a84ed62422366239c'))
 paddle.fluid.DistributeTranspiler ('paddle.fluid.transpiler.distribute_transpiler.DistributeTranspiler', ('document', 'b2b19821c5dffcd11473d6a4eef089af'))
 paddle.fluid.DistributeTranspiler.__init__ (ArgSpec(args=['self', 'config'], varargs=None, keywords=None, defaults=(None,)), ('document', '6adf97f83acf6453d4a6a4b1070f3754'))
 paddle.fluid.DistributeTranspiler.get_pserver_program (ArgSpec(args=['self', 'endpoint'], varargs=None, keywords=None, defaults=None), ('document', 'b1951949c6d21698290aa8ac69afee32'))

python/paddle/fluid/executor.py

@@ -66,11 +66,21 @@ def _switch_scope(scope):
 @signature_safe_contextmanager
 def scope_guard(scope):
     """
-    Change the global/default scope instance by Python `with` statement. All
-    variable in runtime will assigned to the new scope.
+    This function switches scope through python `with` statement.
+    Scope records the mapping between variable names and variables ( :ref:`api_guide_Variable` ),
+    similar to brackets in programming languages.
+    If this function is not invoked, all variables and variable names are recorded in the default global scope.
+    When users need to create variables with the same name,
+    they need to switch scopes through this function
+    if they do not want the mapping of variables with the same name to be overwritten.
+    After switching through the `with` statement,
+    all variables created in the `with` block will be assigned to a new scope.
+
+    Parameters:
+        scope: The new scope.
 
-    Args:
-        scope: The new global/default scope.
+    Returns:
+        None
 
     Examples:
         .. code-block:: python