From cb72857710ebe008a4c18f2c421d315ab8ec70ac Mon Sep 17 00:00:00 2001
From: Young <afe.young@gmail.com>
Date: Tue, 6 Jul 2021 05:20:53 +0000
Subject: [PATCH] fix annotation recursive error

---
 qlib/backtest/__init__.py | 12 ++++++++++--
 qlib/backtest/backtest.py |  7 ++++++-
 2 files changed, 16 insertions(+), 3 deletions(-)

diff --git a/qlib/backtest/__init__.py b/qlib/backtest/__init__.py
index 0de290f02..b2c3f8c09 100644
--- a/qlib/backtest/__init__.py
+++ b/qlib/backtest/__init__.py
@@ -1,9 +1,13 @@
 # Copyright (c) Microsoft Corporation.
 # Licensed under the MIT License.
+from __future__ import annotations
 import copy
-from typing import Union
+from typing import Union, TYPE_CHECKING
 
 from .account import Account
+
+if TYPE_CHECKING:
+    from ..strategy.base import BaseStrategy
 from .exchange import Exchange
 from .executor import BaseExecutor
 from .backtest import backtest_loop
@@ -11,7 +15,6 @@ from .backtest import collect_data_loop
 from .utils import CommonInfrastructure
 from .order import Order
 
-from ..strategy.base import BaseStrategy
 from ..utils import init_instance_by_config
 from ..log import get_module_logger
 from ..config import C
@@ -137,6 +140,11 @@ def get_strategy_executor(
     pos_type: str = "Position",
 ):
 
+    # NOTE:
+    # - for avoiding recursive import
+    # - typing annotations is not reliable
+    from ..strategy.base import BaseStrategy
+
     trade_account = create_account_instance(
         start_time=start_time, end_time=end_time, benchmark=benchmark, account=account, pos_type=pos_type
     )
diff --git a/qlib/backtest/backtest.py b/qlib/backtest/backtest.py
index 0ac4581da..48d06db6c 100644
--- a/qlib/backtest/backtest.py
+++ b/qlib/backtest/backtest.py
@@ -1,7 +1,12 @@
 # Copyright (c) Microsoft Corporation.
 # Licensed under the MIT License.
+
+from __future__ import annotations
 from qlib.backtest.order import BaseTradeDecision
-from qlib.strategy.base import BaseStrategy
+from typing import TYPE_CHECKING
+
+if TYPE_CHECKING:
+    from qlib.strategy.base import BaseStrategy
 from qlib.backtest.executor import BaseExecutor
 from ..utils.time import Freq
 from tqdm.auto import tqdm