From c414f561f6d37d2e23c3c3e13decac9e3841168f Mon Sep 17 00:00:00 2001
From: nanoric <nanoric@qq.com>
Date: Fri, 15 Mar 2019 03:07:01 -0400
Subject: [PATCH] =?UTF-8?q?[Add]=20BaseGateway:=20=E5=A2=9E=E5=8A=A0?=
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---
 vnpy/trader/gateway.py | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/vnpy/trader/gateway.py b/vnpy/trader/gateway.py
index 598120c3..2442f990 100644
--- a/vnpy/trader/gateway.py
+++ b/vnpy/trader/gateway.py
@@ -36,6 +36,8 @@ class BaseGateway(ABC):
 
     # How to implement a gateway:
 
+    ---
+    ## Basics
     A gateway should satisfies:
     * this class should be thread-safe:
         * all methods should be thread-safe
@@ -44,10 +46,12 @@ class BaseGateway(ABC):
     * satisfies all requirements written in docstring for every method and callbacks.
     * automatically reconnect if connection lost.
 
-    methods must implements:
+    ---
+    ## methods must implements:
     all @abstractmethod
 
-    callbacks must response manually:
+    ---
+    ## callbacks must response manually:
     * on_tick
     * on_trade
     * on_order
@@ -55,6 +59,13 @@ class BaseGateway(ABC):
     * on_account
     * on_contract
 
+    All the XxxData passed to callback should be constant, which means that
+        the object should not be modified after passing to on_xxxx.
+    So if you use a cache to store reference of data, use copy.copy to create a new object
+    before passing that data into on_xxxx
+
+
+
     """
 
     # Fields required in setting dict for connect function.