From 9bae7944f23cd4fad3fbb0cfb04425e2c06a1ef0 Mon Sep 17 00:00:00 2001
From: "Dante (Kuo-Jung) Su" <dante.su@broadcom.com>
Date: Wed, 13 Nov 2019 08:57:56 +0800
Subject: [PATCH] [sonic_platform_base] Reallocate empty lists in the
 constructor of the base class (#65)

Signed-off-by: Dante (Kuo-Jung) Su <dante.su@broadcom.com>
---
 sonic_platform_base/chassis_base.py | 20 ++++++++++++++------
 sonic_platform_base/module_base.py  | 17 ++++++++++++-----
 sonic_platform_base/psu_base.py     |  5 ++++-
 3 files changed, 30 insertions(+), 12 deletions(-)

diff --git a/sonic_platform_base/chassis_base.py b/sonic_platform_base/chassis_base.py
index 4e1762699e9a..eb1e089b564d 100644
--- a/sonic_platform_base/chassis_base.py
+++ b/sonic_platform_base/chassis_base.py
@@ -28,27 +28,27 @@ class ChassisBase(device_base.DeviceBase):
 
     # List of ComponentBase-derived objects representing all components
     # available on the chassis
-    _component_list = []
+    _component_list = None
 
     # List of ModuleBase-derived objects representing all modules
     # available on the chassis (for use with modular chassis)
-    _module_list = []
+    _module_list = None
 
     # List of FanBase-derived objects representing all fans
     # available on the chassis
-    _fan_list = []
+    _fan_list = None
 
     # List of PsuBase-derived objects representing all power supply units
     # available on the chassis
-    _psu_list = []
+    _psu_list = None
 
     # List of ThermalBase-derived objects representing all thermals
     # available on the chassis
-    _thermal_list = []
+    _thermal_list = None
 
     # List of SfpBase-derived objects representing all sfps
     # available on the chassis
-    _sfp_list = []
+    _sfp_list = None
 
     # Object derived from WatchdogBase for interacting with hardware watchdog
     _watchdog = None
@@ -56,6 +56,14 @@ class ChassisBase(device_base.DeviceBase):
     # Object derived from eeprom_tlvinfo.TlvInfoDecoder indicating the eeprom on the chassis
     _eeprom = None
 
+    def __init__(self):
+        self._component_list = []
+        self._module_list = []
+        self._fan_list = []
+        self._psu_list = []
+        self._thermal_list = []
+        self._sfp_list = []
+
     def get_base_mac(self):
         """
         Retrieves the base MAC address for the chassis
diff --git a/sonic_platform_base/module_base.py b/sonic_platform_base/module_base.py
index b4f8ac4514f1..6a7d2a7d567a 100644
--- a/sonic_platform_base/module_base.py
+++ b/sonic_platform_base/module_base.py
@@ -19,23 +19,30 @@ class ModuleBase(device_base.DeviceBase):
 
     # List of ComponentBase-derived objects representing all components
     # available on the module
-    _component_list = []
+    _component_list = None
 
     # List of FanBase-derived objects representing all fans
     # available on the module 
-    _fan_list = []
+    _fan_list = None
 
     # List of PsuBase-derived objects representing all power supply units
     # available on the module
-    _psu_list = []
+    _psu_list = None
 
     # List of ThermalBase-derived objects representing all thermals
     # available on the module
-    _thermal_list = []
+    _thermal_list = None
 
     # List of SfpBase-derived objects representing all sfps
     # available on the module
-    _sfp_list = []
+    _sfp_list = None
+
+    def __init__(self):
+        self._component_list = []
+        self._fan_list = []
+        self._psu_list = []
+        self._thermal_list = []
+        self._sfp_list = []
 
     def get_base_mac(self):
         """
diff --git a/sonic_platform_base/psu_base.py b/sonic_platform_base/psu_base.py
index adb1a6051db0..0341a50e0e44 100644
--- a/sonic_platform_base/psu_base.py
+++ b/sonic_platform_base/psu_base.py
@@ -23,7 +23,10 @@ class PsuBase(device_base.DeviceBase):
 
     # List of FanBase-derived objects representing all fans
     # available on the PSU
-    _fan_list = []
+    _fan_list = None
+
+    def __init__(self):
+        self._fan_list = []
 
     def get_num_fans(self):
         """