Yaml Environment Variables in Silverstripe 3

<%- if @topic_view.topic.tags.present? %>
<%= t 'js.tagging.tags' %>: <%- @topic_view.topic.tags.each do |t| %> <%= t %> <%- end %>
<% end %>

Silverstripe Version:
3.7.3

Question:

Is there a way in Silverstripe 3 to include environment variables in the yaml config files, in the same way as the backticks does in 4?

I recently discovered that you can’t :frowning: except in Injector config. There’s a note in the docs about that limitation but it doesn’t say why.

Perhaps you can use Injector config to set a property on any class though? Injector remains a bit of a mystery to me.

Edit: I got this question flipped around, sorry! Not sure about SS3.