class IRB::Context

def initialize(irb, workspace = nil, input_method = nil)

+other+:: uses this as InputMethod
+String+:: uses a File
+nil+:: uses stdin or Reline or Readline

The optional +input_method+ argument:

Creates a new IRB context.
def initialize(irb, workspace = nil, input_method = nil)
  @irb = irb
  if workspace
    @workspace = workspace
  else
    @workspace = WorkSpace.new
  end
  @thread = Thread.current
  # copy of default configuration
  @ap_name = IRB.conf[:AP_NAME]
  @rc = IRB.conf[:RC]
  @load_modules = IRB.conf[:LOAD_MODULES]
  if IRB.conf.has_key?(:USE_SINGLELINE)
    @use_singleline = IRB.conf[:USE_SINGLELINE]
  elsif IRB.conf.has_key?(:USE_READLINE) # backward compatibility
    @use_singleline = IRB.conf[:USE_READLINE]
  else
    @use_singleline = nil
  end
  if IRB.conf.has_key?(:USE_MULTILINE)
    @use_multiline = IRB.conf[:USE_MULTILINE]
  elsif IRB.conf.has_key?(:USE_RELINE) # backward compatibility
    warn <<~MSG.strip
      USE_RELINE is deprecated, please use USE_MULTILINE instead.
    MSG
    @use_multiline = IRB.conf[:USE_RELINE]
  elsif IRB.conf.has_key?(:USE_REIDLINE)
    warn <<~MSG.strip
      USE_REIDLINE is deprecated, please use USE_MULTILINE instead.
    MSG
    @use_multiline = IRB.conf[:USE_REIDLINE]
  else
    @use_multiline = nil
  end
  @use_autocomplete = IRB.conf[:USE_AUTOCOMPLETE]
  @verbose = IRB.conf[:VERBOSE]
  @io = nil
  self.inspect_mode = IRB.conf[:INSPECT_MODE]
  self.use_tracer = IRB.conf[:USE_TRACER] if IRB.conf[:USE_TRACER]
  self.use_loader = IRB.conf[:USE_LOADER] if IRB.conf[:USE_LOADER]
  self.eval_history = IRB.conf[:EVAL_HISTORY] if IRB.conf[:EVAL_HISTORY]
  @ignore_sigint = IRB.conf[:IGNORE_SIGINT]
  @ignore_eof = IRB.conf[:IGNORE_EOF]
  @back_trace_limit = IRB.conf[:BACK_TRACE_LIMIT]
  self.prompt_mode = IRB.conf[:PROMPT_MODE]
  if IRB.conf[:SINGLE_IRB] or !defined?(IRB::JobManager)
    @irb_name = IRB.conf[:IRB_NAME]
  else
    @irb_name = IRB.conf[:IRB_NAME]+"#"+IRB.JobManager.n_jobs.to_s
  end
  @irb_path = "(" + @irb_name + ")"
  case input_method
  when nil
    @io = nil
    case use_multiline?
    when nil
      if STDIN.tty? && IRB.conf[:PROMPT_MODE] != :INF_RUBY && !use_singleline?
        # Both of multiline mode and singleline mode aren't specified.
        @io = RelineInputMethod.new
      else
        @io = nil
      end
    when false
      @io = nil
    when true
      @io = RelineInputMethod.new
    end
    unless @io
      case use_singleline?
      when nil
        if (defined?(ReadlineInputMethod) && STDIN.tty? &&
            IRB.conf[:PROMPT_MODE] != :INF_RUBY)
          @io = ReadlineInputMethod.new
        else
          @io = nil
        end
      when false
        @io = nil
      when true
        if defined?(ReadlineInputMethod)
          @io = ReadlineInputMethod.new
        else
          @io = nil
        end
      else
        @io = nil
      end
    end
    @io = StdioInputMethod.new unless @io
  when '-'
    @io = FileInputMethod.new($stdin)
    @irb_name = '-'
    @irb_path = '-'
  when String
    @io = FileInputMethod.new(input_method)
    @irb_name = File.basename(input_method)
    @irb_path = input_method
  else
    @io = input_method
  end
  self.save_history = IRB.conf[:SAVE_HISTORY] if IRB.conf[:SAVE_HISTORY]
  @extra_doc_dirs = IRB.conf[:EXTRA_DOC_DIRS]
  @echo = IRB.conf[:ECHO]
  if @echo.nil?
    @echo = true
  end
  @echo_on_assignment = IRB.conf[:ECHO_ON_ASSIGNMENT]
  if @echo_on_assignment.nil?
    @echo_on_assignment = :truncate
  end
  @newline_before_multiline_output = IRB.conf[:NEWLINE_BEFORE_MULTILINE_OUTPUT]
  if @newline_before_multiline_output.nil?
    @newline_before_multiline_output = true
  end
  @command_aliases = IRB.conf[:COMMAND_ALIASES]
end