Migrations-looping through add_column lines

sure you could do that, but the problem is that most likely your
columns are going to have more differences than just the name of the
column, so you'd have to structure your loops around you individual
columns...when its all said and done, it would most likely have just
been easier to spell each one out. not only that, but the method that
everyone tends to use is very readable.

ex:

# all same type, easy enough
[:name, :description, :location].each do |col|
  add_column col, :string
end

now try that when all your columns are different types, lengths, not
null, unique, have default values, etc...not so easy now.