---
layout: stdlib-reference
---

# attribute [constref]

> #### Internal Feature
> The feature described in this page is marked as an internal implementation detail, and is not intended for use by end-users.
> Users are advised to avoid using this declaration directly, as it may be removed or changed in future releases.

## Description

Marks a member function to make <span class='code'>this</span> argument passed by const reference.


## Signature

<pre>
[<a href="constref.html">constref</a>]
</pre>