ROS2 Importerror：无法导入名称＆＃x27; generate_py＆＃x27;从＆＃x27; rosidl_generator_py＆＃x27;

Question

我在尝试创建一个自定义界面的同时，按照ROS2教程创建自定义msg和srv文件。该项目看起来像这样：

src/tutorial_interfaces/
├── CMakeLists.txt
├── include
│   └── tutorial_interfaces
├── msg
│   └── Num.msg
├── package.xml
├── src
└── srv
    └── AddThreeInts.srv

我遵循所有步骤，但是 步骤 5构建tutorial_interfaces软件包命令

colcon build -packages-select tutorial_interfaces

失败了以下错误消息：

Starting >>> tutorial_interfaces
--- stderr: tutorial_interfaces                             
Traceback (most recent call last):
  File "/opt/ros/humble/share/rosidl_generator_py/cmake/../../../lib/rosidl_generator_py/rosidl_generator_py", line 8, in <module>
    from rosidl_generator_py import generate_py
ImportError: cannot import name 'generate_py' from 'rosidl_generator_py'

有人知道如何解决这个问题吗？

系统：Ubuntu 22.04 + ROS2 Humble

Answer 1

通过安装依赖项来解决此问题，

pip install empy
pip install lark

我基本上查看了错误，并在位于此处的系统上看到了它是从rosidl_generator_py中导入generate_py

/opt/ros/humble/local/lib/python3.10/dist-packages/rosidl_generator_py/__init__.py

我 目录，启动Python，并尝试了

from generate_py_impl import generate_py

那里，我得到了有关错误的更多详细信息，错误基本上说我缺少Python依赖关系。

因此，您可能会缺少比我更多的依赖关系，如果是的话，请转到该目录并尝试自己导入它，口译员会告诉您您所缺少的内容。

Answer 2

我面临同一问题（同一系统）

系统：Ubuntu 22.04 + ROS2 Humble

colcon build                                                                                          ─╯
[0.370s] WARNING:colcon.colcon_core.package_selection:Some selected packages are already built in one or more underlay workspaces:
    'turtlesim' is in: /opt/ros/humble
If a package in a merged underlay workspace is overridden and it installs headers, then all packages in the overlay must sort their include directories by workspace order. Failure to do so may result in build failures or undefined behavior at run time.
If the overridden package is used by another package in any underlay, then the overriding package in the overlay must be API and ABI compatible or undefined behavior at run time may occur.

If you understand the risks and want to override a package anyways, add the following to the command line:
    --allow-overriding turtlesim

This may be promoted to an error in a future release of colcon-override-check.
Starting >>> turtlesim
--- stderr: turtlesim                             
Traceback (most recent call last):
  File "/opt/ros/humble/share/rosidl_generator_py/cmake/../../../lib/rosidl_generator_py/rosidl_generator_py", line 8, in <module>
    from rosidl_generator_py import generate_py
ImportError: cannot import name 'generate_py' from 'rosidl_generator_py' (/opt/ros/humble/local/lib/python3.10/dist-packages/rosidl_generator_py/__init__.py)
gmake[2]: *** [turtlesim__py/CMakeFiles/turtlesim__py.dir/build.make:121: rosidl_generator_py/turtlesim/_turtlesim_s.ep.rosidl_typesupport_fastrtps_c.c] Error 1
gmake[1]: *** [CMakeFiles/Makefile2:706: turtlesim__py/CMakeFiles/turtlesim__py.dir/all] Error 2
gmake[1]: *** Waiting for unfinished jobs....
gmake: *** [Makefile:146: all] Error 2
---
Failed   <<< turtlesim [0.48s, exited with code 2]

Summary: 0 packages finished [0.64s]
  1 package failed: turtlesim
  1 package had stderr output: turtlesim

Answer 3

我在同一系统设置Ubuntu 22.04和Ros2 Humble上也有同样的问题。还有一件事是，我激活了Anaconda。我通过停用conda env并重新构建包装来解决问题。希望它可以帮助大家解决问题。

Answer 4

最近，我在编译具有自定义接口定义的不同软件包时遇到了相同的错误。

Traceback (most recent call last):
  File "/opt/ros/humble/share/rosidl_generator_py/cmake/../../../lib/rosidl_generator_py/rosidl_generator_py", line 8, in <module>
    from rosidl_generator_py import generate_py
ImportError: cannot import name 'generate_py'

我没有anaconda或conda已安装，所以我无法脱离它。因此，我通过在cmakelists.txt中评论此行来修复它：

# find_package(rosidl_default_generators REQUIRED)

我敢肯定可能有更好的方法。但是我不确定是否有一种方法可以通过colcon使用哪种版本的Python，并且该版本是否可以导入generate_py。