Add Useful ActiveSupport Constants For Durations as a Rails TIL

rails/useful-active-support-constants-for-durations.md

@@ -0,0 +1,45 @@
+# Useful ActiveSupport Constants For Durations
+
+Whenever I'm passing a duration to a function, I like to [name it with the
+unit](https://ruudvanasseldonk.com/2022/03/20/please-put-units-in-names)
+relative to the value it represents. For instance, if I need to pass in an hour
+duration in seconds, I might write the following line:
+
+```ruby
+hour_in_seconds = 60 * 60
+
+# or
+
+hour_in_seconds = 3600
+```
+
+ActiveSupport has a [Duration
+class](https://api.rubyonrails.org/classes/ActiveSupport/Duration.html) with a
+series of constants that we can reach for.
+
+```ruby
+> ActiveSupport::Duration::SECONDS_PER_MINUTE
+=> 60
+> ActiveSupport::Duration::SECONDS_PER_HOUR
+=> 3600
+> ActiveSupport::Duration::SECONDS_PER_DAY
+=> 86400
+> ActiveSupport::Duration::SECONDS_PER_WEEK
+=> 604800
+> ActiveSupport::Duration::SECONDS_PER_MONTH
+=> 2629746
+> ActiveSupport::Duration::SECONDS_PER_YEAR
+=> 31556952
+```
+
+Though it is fun to know about these, we should keep in mind that this class
+provides support for what is likely to be a more useful abstraction layer:
+
+```ruby
+> 1.hour
+=> 1 hour
+> 3.hours
+=> 3 hours
+> 1.day.to_i
+=> 86400
+```