class Tilt::Template

def initialize(file=nil, line=1, options={}, &block)

time this template subclass has been initialized.
The #initialize_engine method is called if this is the very first

file is nil, a block is required.
is given, it should read template data and return as a String. When
default, template data is read from the file specified. When a block
Create a new template with the file, line, and options specified. By 
def initialize(file=nil, line=1, options={}, &block)
  raise ArgumentError, "file or block required" if file.nil? && block.nil?
  options, line = line, 1 if line.is_a?(Hash)
  @file = file
  @line = line || 1
  @options = options || {}
  @reader = block || lambda { |t| File.read(file) }
  @data = nil
  if !self.class.engine_initialized
    initialize_engine
    self.class.engine_initialized = true
  end
end