ROS2以特定值初始化geometry_msgs::Point32
对于ros2的geometry_msgs::msg::Point32来说，其默认的构造函数都是使用initializer将成员 x y z 都初始化为 0，那么有没有办法直接初始化为特定的值呢？资料1提供了一种方法：
// 在 point32_builder.hpp 中提供了如何直接以特定的值初始化point32
struct P
{
float x;
float y;
float z;
}p;
geometry_msgs::build<geometry_msgs::msg::Point32>().x(p.x).y(p.y).z(p.z);
下面给出point32__builder.hpp的文件内容，一看就明白了：
// generated from rosidl_generator_cpp/resource/idl__builder.hpp.em
// with input from geometry_msgs:msg/Point32.idl
// generated code does not contain a copyright notice
#ifndef GEOMETRY_MSGS__MSG__DETAIL__POINT32__BUILDER_HPP_
#define GEOMETRY_MSGS__MSG__DETAIL__POINT32__BUILDER_HPP_
#include <algorithm>
#include <utility>
#include "geometry_msgs/msg/detail/point32__struct.hpp"
#include "rosidl_runtime_cpp/message_initialization.hpp"
namespace geometry_msgs
{
namespace msg
{
namespace builder
{
class Init_Point32_z
{
public:
explicit Init_Point32_z(::geometry_msgs::msg::Point32 & msg)
: msg_(msg)
{}
::geometry_msgs::msg::Point32 z(::geometry_msgs::msg::Point32::_z_type arg)
{
msg_.z = std::move(arg);
return std::move(msg_);
}
private:
::geometry_msgs::msg::Point32 msg_;
};
class Init_Point32_y
{
public:
explicit Init_Point32_y(::geometry_msgs::msg::Point32 & msg)
: msg_(msg)
{}
Init_Point32_z y(::geometry_msgs::msg::Point32::_y_type arg)
{
msg_.y = std::move(arg);
return Init_Point32_z(msg_);
}
private:
::geometry_msgs::msg::Point32 msg_;
};
class Init_Point32_x
{
public:
Init_Point32_x()
: msg_(::rosidl_runtime_cpp::MessageInitialization::SKIP)
{}
Init_Point32_y x(::geometry_msgs::msg::Point32::_x_type arg)
{
msg_.x = std::move(arg);
return Init_Point32_y(msg_);
}
private:
::geometry_msgs::msg::Point32 msg_;
};
} // namespace builder
} // namespace msg
template<typename MessageType>
auto build();
template<>
inline
auto build<::geometry_msgs::msg::Point32>()
{
return geometry_msgs::msg::builder::Init_Point32_x();
}
} // namespace geometry_msgs
#endif // GEOMETRY_MSGS__MSG__DETAIL__POINT32__BUILDER_HPP_