config.assets.precompile

gistfile1.rb

def compile_asset?(path)
  # ignores any filename that begins with '_' (e.g. sass partials)
  # all other css/js/sass/image files are processed
  if File.basename(path) =~ /^[^_].*\.\w+$/
    puts "Compiling: #{path}"
    true
  else
    puts "Ignoring: #{path}"
    false
  end
end

config.assets.precompile = [ method(:compile_asset?).to_proc ]

try putting the method in the outer scope:

 #the absolute beginning of the production.rb file
def compile_asset?(path)
  if File.basename(path) =~ /^[^_].*\.\w+$/
    puts "Compiling: #{path}"
    true
  else
    puts "Ignoring: #{path}"
    false
  end
end
SomeApplicationName::Application.configure do
   config.assets.precompile = [ method(:compile_asset?).to_proc ]
#...some other config stuff
end

Thank you! 👏

just amazing!