ROS Noetic环境下无法导入自定义Python类的问题求助

环境信息 #

• Python 3.8.10
• Ubuntu 20.04
• ROS Noetic

错误日志 #

Traceback (most recent call last):
  File "/home/belal/git/decision_making_pacbot/devel/lib/ros_planning/ros_plan.py", line 15, in <module>
    exec(compile(fh.read(), python_script, 'exec'), context)
  File "/home/belal/git/decision_making_pacbot/src/ros_planning/src/ros_planning/ros_plan.py", line 8, in <module>
    from problem_handler import ProblemHandler
ImportError: cannot import name 'ProblemHandler' from 'problem_handler' (/home/belal/git/decision_making_pacbot/devel/.private/ros_planning/lib/ros_planning/problem_handler.py)

文件层级结构 #

src
├── ros_planning
│   ├── CMakeLists.txt
|   ├── package.xml
|   ├── setup.py
│   └── src
│       └── ros_planning
|           ├── ros_plan.py
|           ├── problem_handler.py
|           └── __init__.py

配置文件内容 #

CMakeLists.txt #

cmake_minimum_required(VERSION 3.0.2)
project(ros_planning)

find_package(catkin REQUIRED COMPONENTS rospy)

catkin_package(CATKIN_DEPENDS)

catkin_install_python(PROGRAMS
  src/${PROJECT_NAME}/problem_handler.py
  src/${PROJECT_NAME}/ros_plan.py
  DESTINATION ${CATKIN_PACKAGE_BIN_DESTINATION}
)
catkin_python_setup()

install(DIRECTORY model downward launch DESTINATION "${CATKIN_PACKAGE_SHARE_DESTINATION}")

package.xml #

<?xml version="1.0"?>
<package format="2">
  <name>ros_planning</name>
  <version>0.0.0</version>
  <description>The ros_planning package</description>
  <maintainer email="s@todo.todo">s</maintainer>
  <license>MIT</license>
  <buildtool_depend>catkin</buildtool_depend>
  <build_depend>roscpp</build_depend>
  <build_depend>rospy</build_depend>
  <build_depend>std_msgs</build_depend>
  <build_export_depend>roscpp</build_export_depend>
  <build_export_depend>rospy</build_export_depend>
  <build_export_depend>std_msgs</build_export_depend>
  <exec_depend>roscpp</exec_depend>
  <exec_depend>rospy</exec_depend>
  <exec_depend>std_msgs</exec_depend>
</package>

setup.py #

#!/usr/bin/python3
from distutils.core import setup
from catkin_pkg.python_setup import generate_distutils_setup

setup_args = generate_distutils_setup(
    scripts=['src/ros_planning/problem_handler.py', 'src/ros_planning/ros_plan.py'],
    packages=['ros_planning'],
    package_dir={'': 'src'},
    requires=['rospy', 'std_msgs']
)
setup(**setup_args)

相关代码片段 #

problem_handler.py中的类定义：

class ProblemHandler:
    def __init__(self, path):
        self.path = path

ros_plan.py中的导入语句：

from problem_handler import ProblemHandler

解决方案 #

1. 修正导入语句 #

ROS Noetic基于Python3，相对导入规则更严格，需替换原有导入方式：

• 方式一：使用完整包路径导入

  from ros_planning.problem_handler import ProblemHandler
  

• 方式二：使用包内相对导入

  from .problem_handler import ProblemHandler
  

2. 调整CMakeLists.txt执行顺序 #

catkin_python_setup()必须在catkin_install_python()前执行，同时移除库模块的PROGRAMS配置：
修改后的CMakeLists.txt：

cmake_minimum_required(VERSION 3.0.2)
project(ros_planning)

find_package(catkin REQUIRED COMPONENTS rospy)

catkin_package(CATKIN_DEPENDS)

# 优先执行Python包配置
catkin_python_setup()

# 仅安装可执行脚本，库模块由catkin_python_setup自动处理
catkin_install_python(PROGRAMS
  src/${PROJECT_NAME}/ros_plan.py
  DESTINATION ${CATKIN_PACKAGE_BIN_DESTINATION}
)

install(DIRECTORY model downward launch DESTINATION "${CATKIN_PACKAGE_SHARE_DESTINATION}")

3. 清理编译空间并重新编译 #

catkin clean --all
catkin_make
source devel/setup.bash

原因说明 #

• Python3对相对导入的兼容性要求比Python2（ROS Melodic使用版本）更严格，旧导入方式不再适用。
• CMake配置顺序错误，导致库模块被当作可执行脚本安装，破坏了包内模块的正常引用路径。

内容的提问来源于stack exchange，提问作者Bilal