ROS2 Topic Subscription Using Lambda Funtction

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You didn't include any error output in your question (please always do this) but I'm guessing you got some very cryptic compiler errors involving subscription callbacks. If so, it's because a callback that receives a message by value is not supported as you have in your lambda function. I could not find any documentation for this but this github PR details the allowed callback types which includes a few new ones from Galactic onwards (const geometry_msgs::msg::Point&). For Foxy, your best bet is to change the message type to geometry_msgs::msg::Point::SharedPtr (more common) or UniquePtr (more correct).