2 Matching Annotations
  1. Mar 2021
  2. Feb 2021
    1. There are times where it is useful to know whether a value was passed to run or the result of a filter default. In particular, it is useful when nil is an acceptable value.

      Yes! An illustration in ruby:

      main > h = {key_with_nil_value: nil}
      => {:key_with_nil_value=>nil}
      
      main > h[:key_with_nil_value]
      => nil
      
      main > h[:missing_key]  # this would be undefined in JavaScript (a useful distinction) rather than null, but in Ruby it's indistinguishable from the case where a nil value was actually explicitly _supplied_ by the caller/user
      => nil
      
      # so we have to check for "missingness" ("undefinedness"?) differently in Ruby
      
      main > h.key?(:key_with_nil_value)
      => true
      
      main > h.key?(:missing_key)
      => false
      

      This is one unfortunate side effect of Ruby having only nil and no built-in way to distinguish between null and undefined like in JavaScript.