From: "Sean E. McCardell" <sean@...>
Date: 2005-04-29T07:01:15+09:00
Subject: Re: [SOLUTION] HighLine (#29) [LONG]

On 11:52 Thu 28 Apr     , James Edward Gray II wrote:
> Any chance you could give us a few simple examples of usage?  For 
> example, how do the quiz examples translate to this system?

Sure thing. Here goes:

require 'highline'

# This might be useful for someone implementing COMMAND.COM in Ruby :)

class DiskError < HighLine::ChoiceInput
  choices "abort", "retry", "fail"
  synonym "abort", "a"
  synonym "retry", "r"
  synonym "fail", "f"
end

result = DiskError.ask("Error reading drive A:")

# And the output will look like:
#   Error reading drive A: [abort/retry/fail]
# The user will continue to be prompted until "abort", "retry", or
# "fail" is entered (or one of their synonyms, "a", "r", or "f"

# For the age example from the quiz, I would do:

class IntegerInput < HighLine::ValueInput
  validate /^\d+$/
  # when a validation procedure returns a three-element array,
  # the second element can be an error message, and the third
  # element will be used as an alternate test value (instead of the
  # user's response string) for subsequent validation tests.
  validate proc { |r| [true, nil, r.to_i] }
end

age = IntegerInput.ask("Enter your age:") {
  validate :between?, 0, 105
}.alternate

# The #alternate method of the returned object gives you access to
# the alternate test value, if any, created during validation. In this
# case, it is an Integer

# And for an indirect way of finding an age, here's one that demonstrates
# using an instance method for validation:

require 'date'
class DateInput < HighLine::ValueInput
  validate :with_my, :ensure_date

  def ensure_date(response)
    begin
      test_date = Date.parse(response)
    rescue ArgumentError
      false
    else
      [true, nil, test_date]
    end
  end
end

birthday = DateInput.ask("When were you born?") {
  # output_format, like validate, operates on an alternate test value
  # if one was created during validation. This just calls #to_s on that
  # value, so you always get anwers in the form "YYYY-MM-DD", even if
  # you enter something like "April 28th, 2005"
  output_format :to_s
  error_message "Please enter a valid date"
  validate proc { |r| [r <= Date.today, "You can't be from the future!"] }
}

Hope this helps,

--Sean