As a developer, it’s important for me to keep up to date with latest technology and code. Using depreciated functions while developing a WordPress site is really a bad idea. As WordPress keeps updated for bug fixes and improvement, some functions and hooks get deprecated and therefore it should no longer be used.
If you’re a blogger writing about the code in your site, it’s very recommended to show notification in the post to discourage your readers from using it as the code is no longer can be used or deprecated.
Here’s an example of the notification that you’ll see on some of Bill’s old articles.
Once installed, you’ll see a new meta box to mark any post as old. From the plugin’s settings page, you can define a default notification that will show up whenever the post is marked as old. Additionally, there’s a text area where you can put a custom note for the readers that will overwrite the default note.