Fix default function parameter assignment to a list

With python you should not assign a list as the default value of a
function parameter - because a list is mutable, the result will be that
the first time a value is passed it will actually modify the default.
Reference:

http://docs.python-guide.org/en/latest/writing/gotchas/#mutable-default-arguments

Signed-off-by: Paul Eggleton <paul.eggleton@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

1 files changed, 9 insertions, 3 deletions

diff --git a/lib/bb/ui/crumbs/hobeventhandler.py b/lib/bb/ui/crumbs/hobeventhandler.py
index 43edb70b08..b71fb33d30 100644
--- a/lib/bb/ui/crumbs/hobeventhandler.py
+++ b/lib/bb/ui/crumbs/hobeventhandler.py
@@ -440,11 +440,17 @@ class HobHandler(gobject.GObject):
         self.commands_async.append(self.SUB_BUILD_RECIPES)
         self.run_next_command(self.GENERATE_PACKAGES)
 
-    def generate_image(self, image, base_image, image_packages=[], toolchain_packages=[], default_task="build"):
+    def generate_image(self, image, base_image, image_packages=None, toolchain_packages=None, default_task="build"):
         self.image = image
         self.base_image = base_image
-        self.package_queue = image_packages
-        self.toolchain_packages = toolchain_packages
+        if image_packages:
+            self.package_queue = image_packages
+        else:
+            self.package_queue = []
+        if toolchain_packages:
+            self.toolchain_packages = toolchain_packages
+        else:
+            self.toolchain_packages = []
         self.default_task = default_task
         self.runCommand(["setPrePostConfFiles", "conf/.hob.conf", ""])
         self.commands_async.append(self.SUB_PARSE_CONFIG)