ros2中创建一个python package

完整的python package的目录结构如下:

• source /opt/ros/dashing/setup.bash
• cd ros2_ws/src && ros2 pkg create <package_name>
• Delete CMakeLists.txt , create setup.py and setup.cfg and edit package.xml
  
  setup.py内容参考:

from setuptools import setup

package_name = 'ros2_demo_py'

setup(
    name=package_name,
    version='0.7.0',
    packages=[package_name],
    install_requires=['setuptools'],
    zip_safe=True,
    author='You',
    author_email='you@youremail.com',
    maintainer='YourFirstname Lastname',
    maintainer_email='your@youremail.com',
    keywords=['ROS'],
    classifiers=[
        'Intended Audience :: Developers',
        'License :: OSI Approved :: Apache Software License',
        'Programming Language :: Python',
        'Topic :: Software Development',
    ],
    description='A simple ROS2 Python package',
    license='Apache License, Version 2.0',
    tests_require=['pytest'],
    entry_points={
        'console_scripts': [
            'demo = ros2_demo_py.demo:main'
        ],
    },
)

fbi warning!!!!!!!!!

'console_scripts': [

'demo = ros2_demo_py.demo:main'

],

告知ros2如何加载脚本.比如ros2 run ros2_demo_py demo实际上就是说要去执行ros2_demo_py/demo.py的main()函数. 更改setup.py后必须重新colcon build才会生效.

当我改成'console_scripts': [

'fuck_ = ros2_demo_py.what:main'

],时,相应的执行命令就变为ros2 run ros2_demo_py fuck_,执行的就是ros2_demo_py/what.py的main()函数

setup.cfg内容参考:

[develop]
script-dir=$base/lib/ros2_demo_py
[install]
install-scripts=$base/lib/ros2_demo_py

package.xml内容参考:

<?xml version="1.0"?>
<?xml-model href="http://download.ros.org/schema/package_format2.xsd" schematypens="http://www.w3.org/2001/XMLSchema"?>
<package format="2">
  <name>ros2_demo_py</name>
  <version>0.7.3</version>
  <description>A simple ROS2 Python package</description>

  <maintainer email="sloretz@openrobotics.org">Shane Loretz</maintainer>
  <license>Apache License 2.0</license>

  <exec_depend>rclpy</exec_depend>
  <exec_depend>std_msgs</exec_depend>

  <!-- These test dependencies are optional
  Their purpose is to make sure that the code passes the linters -->
  <test_depend>ament_copyright</test_depend>
  <test_depend>ament_flake8</test_depend>
  <test_depend>ament_pep257</test_depend>
  <test_depend>python3-pytest</test_depend>

  <export>
    <build_type>ament_python</build_type>
  </export>
</package>

• 创建python代码
  
  demo.py

# Copyright 2016 Open Source Robotics Foundation, Inc.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

import rclpy
from rclpy.node import Node

from std_msgs.msg import String

class MinimalPublisher(Node):

    def __init__(self):
        super().__init__('minimal_publisher')
        self.publisher_ = self.create_publisher(String, 'topic')
        timer_period = 0.5  # seconds
        self.timer = self.create_timer(timer_period, self.timer_callback)
        self.i = 0

    def timer_callback(self):
        msg = String()
        msg.data = 'Hello World: %d' % self.i
        self.publisher_.publish(msg)
        self.get_logger().info('Publishing: "%s"' % msg.data)
        self.i += 1

def main(args=None):
    rclpy.init(args=args)

    minimal_publisher = MinimalPublisher()

    rclpy.spin(minimal_publisher)

    # Destroy the node explicitly
    # (optional - otherwise it will be done automatically
    # when the garbage collector destroys the node object)
    minimal_publisher.destroy_node()
    rclpy.shutdown()

if __name__ == '__main__':
    main()

• 回到workspace目录,编译
  
  user:~/ros2_ws$ colcon build --symlink-install

详细步骤参考:https://www.theconstructsim.com/ros2-tutorials-5-how-to-create-a-ros2-package-for-python-update/