What is boost::bind() commonly used in Action servers

I saw this boost::bind code used multiple times in Action servers and after looking through documentations, i still can’t wrap my head around how and more importantly, why it’s used.

This code is from "Solutions for Unit 4 Actions Part 2"

Also, I was looking through the forum for an answer and realised someone asked this question before 2 years ago but there was no answer for it yet. This question was however, catered towards the Fibonnaci Action in the examples.

I have gotten very good answers from this forum in the past, and i hope this someone here can assist in clearing my doubts.


It might be for passing external context/arguments to your callback. In certain cases you want to pass more things to your callback that what is passed by the caller.

See : https://answers.ros.org/question/12045/how-to-deliver-arguments-to-a-callback-function/

In that case it would be to be able to access this into your callback as well as the parameters that get passed to the callback by the action.

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Hi, just one more thing. In the parameters inside boost::bind, i see a “_1” parameter. This “_1” acts as a placeholder for arguments given to the “executeCB” method right?

And if i’m wrong, what exactly does it represent?