PDF::Writer：PDF::SimpleTable::Column#justification, #justification=

require 'pdf/simpletable'

pdf = PDF::Writer.new

PDF::SimpleTable.new do |tab|
  tab.column_order = %w(col1 col2 col3)

  tab.show_lines    = :all
  tab.show_headings = true
  tab.orientation   = :center
  tab.position      = :center
  tab.columns = {
    "col1" => PDF::SimpleTable::Column.new("COL1") { |col| col.justification = :right  },
    "col2" => PDF::SimpleTable::Column.new("COL2") { |col| col.justification = :center }}
  p tab.columns["col1"].justification
  p tab.columns["col2"].justification

  data = [
    { "col1" => "foo", "col2" => "bar", "col3" => "baz" },
    { "col1" => "foo foo", "col2" => "bar bar", "col3" => "baz baz" },
  ]

  tab.data.replace data
  tab.render_on(pdf)
end

pdf.save_as("2008032000.pdf")

で、

:right
:center