# class Gem::StreamUI

`Gem::StreamUI` implements a simple stream based user interface.

### Attributes

errs [R]

The error stream

ins [R]

The input stream

outs [R]

The output stream

### Public Class Methods

new (in_stream, out_stream, err_stream=$stderr, usetty=true)
Source

    # File lib/rubygems/user_interaction.rb, line 196
    def initialize(in_stream, out_stream, err_stream=$stderr, usetty=true)
      @ins = in_stream
      @outs = out_stream
      @errs = err_stream
      @usetty = usetty
    end

Creates a new `StreamUI` wrapping `in_stream` for user input, `out_stream` for standard output, `err_stream` for error output. If `usetty` is true then special operations (like asking for passwords) will use the TTY commands to disable character echo.

### Public Instance Methods

_gets_noecho ()
Source

    # File lib/rubygems/user_interaction.rb, line 320
    def _gets_noecho
      require_io_console
      @ins.noecho { @ins.gets }
    end

alert (statement, question=nil)
Source

    # File lib/rubygems/user_interaction.rb, line 335
    def alert(statement, question=nil)
      @outs.puts "INFO:  #{statement}"
      ask(question) if question
    end

Display an informational alert. Will ask `question` if it is not nil.

alert_error (statement, question=nil)
Source

    # File lib/rubygems/user_interaction.rb, line 352
    def alert_error(statement, question=nil)
      @errs.puts "ERROR:  #{statement}"
      ask(question) if question
    end

Display an error message in a location expected to get error messages. Will ask `question` if it is not nil.

alert_warning (statement, question=nil)
Source

    # File lib/rubygems/user_interaction.rb, line 343
    def alert_warning(statement, question=nil)
      @errs.puts "WARNING:  #{statement}"
      ask(question) if question
    end

Display a warning on stderr. Will ask `question` if it is not nil.

ask (question)
Source

    # File lib/rubygems/user_interaction.rb, line 284
    def ask(question)
      return nil unless tty?

      @outs.print(question + "  ")
      @outs.flush

      result = @ins.gets
      result&.chomp!
      result
    end

Ask a question. Returns an answer if connected to a tty, nil otherwise.

ask_for_password (question)
Source

    # File lib/rubygems/user_interaction.rb, line 298
    def ask_for_password(question)
      return nil unless tty?

      @outs.print(question, "  ")
      @outs.flush

      password = _gets_noecho
      @outs.puts
      password&.chomp!
      password
    end

Ask for a password. Does not echo response to terminal.

ask_yes_no (question, default=nil)
Source

    # File lib/rubygems/user_interaction.rb, line 249
    def ask_yes_no(question, default=nil)
      unless tty?
        if default.nil?
          raise Gem::OperationNotSupportedError,
                "Not connected to a tty and no default specified"
        else
          return default
        end
      end

      default_answer = case default
                       when nil
                         "yn"
                       when true
                         "Yn"
                       else
                         "yN"
      end

      result = nil

      while result.nil? do
        result = case ask "#{question} [#{default_answer}]"
                 when /^y/i then true
                 when /^n/i then false
                 when /^$/  then default
        end
      end

      result
    end

Ask a question. Returns a true for yes, false for no. If not connected to a tty, raises an exception if default is nil, otherwise returns default.

backtrace (exception)
Source

    # File lib/rubygems/user_interaction.rb, line 214
    def backtrace(exception)
      return unless Gem.configuration.backtrace

      @errs.puts "\t#{exception.backtrace.join "\n\t"}"
    end

Prints a formatted backtrace to the errors stream if backtraces are enabled.

choose_from_list (question, list)
Source

    # File lib/rubygems/user_interaction.rb, line 225
    def choose_from_list(question, list)
      @outs.puts question

      list.each_with_index do |item, index|
        @outs.puts " #{index + 1}. #{item}"
      end

      @outs.print "> "
      @outs.flush

      result = @ins.gets

      return nil, nil unless result

      result = result.strip.to_i - 1
      return nil, nil unless (0...list.size) === result
      [list[result], result]
    end

Choose from a list of options. `question` is a prompt displayed above the list. `list` is a list of option strings. Returns the pair [option_name, option_index].

close ()
Source

    # File lib/rubygems/user_interaction.rb, line 366
    def close
    end

download_reporter (*args)
Source

    # File lib/rubygems/user_interaction.rb, line 499
    def download_reporter(*args)
      if [nil, false].include?(Gem.configuration.verbose) || !@outs.tty?
        SilentDownloadReporter.new(@outs, *args)
      else
        ThreadedDownloadReporter.new(@outs, *args)
      end
    end

Return a download reporter object chosen from the current verbosity

progress_reporter (*args)
Source

    # File lib/rubygems/user_interaction.rb, line 372
    def progress_reporter(*args)
      case Gem.configuration.verbose
      when nil, false
        SilentProgressReporter.new(@outs, *args)
      when true
        SimpleProgressReporter.new(@outs, *args)
      else
        VerboseProgressReporter.new(@outs, *args)
      end
    end

Return a progress reporter object chosen from the current verbosity.

require_io_console ()
Source

    # File lib/rubygems/user_interaction.rb, line 310
    def require_io_console
      @require_io_console ||= begin
        begin
          require "io/console"
        rescue LoadError
        end
        true
      end
    end

say (statement="")
Source

    # File lib/rubygems/user_interaction.rb, line 328
    def say(statement="")
      @outs.puts statement
    end

Display a statement.

terminate_interaction (status = 0)
Source

    # File lib/rubygems/user_interaction.rb, line 361
    def terminate_interaction(status = 0)
      close
      raise Gem::SystemExitException, status
    end

Terminate the application with exit code `status`, running any exit handlers that might have been defined.

tty? ()
Source

    # File lib/rubygems/user_interaction.rb, line 206
    def tty?
      @usetty && @ins.tty?
    end

Returns true if TTY methods should be used on this `StreamUI`.