# class IRB::History

Represents history of results of previously evaluated commands.

Available via `__` variable, only if `IRB.conf[:EVAL_HISTORY]` or `IRB::CurrentContext().eval_history` is non-nil integer value (by default it is `nil`).

Example (in ‘irb`):

    # Initialize history
    IRB::CurrentContext().eval_history = 10
    # => 10

    # Perform some commands...
    1 + 2
    # => 3
    puts 'x'
    # x
    # => nil
    raise RuntimeError
    # ...error raised

    # Inspect history (format is "<item number> <evaluated value>":
    __
    # => 1 10
    # 2 3
    # 3 nil

    __[1]
    # => 10

### Public Instance Methods

[](idx) click to toggle source

Get one item of the content (both positive and negative indexes work).

    # File lib/irb/ext/history.rb, line 113
    def [](idx)
      begin
        if idx >= 0
          @contents.find{|no, val| no == idx}[1]
        else
          @contents[idx][1]
        end
      rescue NameError
        nil
      end
    end