Global macro and how to use it


I have a lot of links in my site, some of them contains http/https and some not. I want to check every link and if it contains http then add target="_blank" to it.

I want to use macro for this, but this theme is unclear in documentation:

  1. In which file should I create this macro and in which folder? It should be a special file like functions.php in WordPress.
  2. How to use it globally in every twig file?

I found macros.html.twig in Antimatter:

but can’t find where this file is included or used:

Help =)

There is no global macro for twig, isn’t it?
I found in Google what I want to achieve:

I was looking for a solution to this, and it turns out it’s just our nomenclature that needs re specifying: A macro is just a function, so we just need to register a function in Twig through a plugin to make it globally available. The docs do not note in much detail (see reference), but just from the PCRE-plugin example I added a needed macro for global use - albeit in a theme because my use-case is theme-specific.