#1 Collecting input

example_1.rb

# No input
def seconds_in_day
  24 * 60 * 60
end

# This is the same as below
SECONDS_IN_DAY = 24 * 60 * 60

example_2.rb

# With input, and it's most unambiguous
def seconds_in_days(num_days) 
  num_days * 24 * 60 * 60
end

example_3.rb

# Input comes from Constant (Class or Module)
class TimeCalc
  SECONDS_IN_DAY = 24 * 60 * 60
  
  def seconds_in_days(num_days)
    num_days * SECONDS_IN_DAY
  end
end

example_4.rb

# Input from another method
class TimeCalc
  def seconds_in_week
      seconds_in_days(7) 
  end
  def seconds_in_days(num_days)
    num_days * SECONDS_IN_DAY
  end 
end

example_5.rb

# From instance varibles
class TimeCalc
    def initialize
      @start_date = Time.now  # indirect input (like constant) 
    end
    def time_n_days_from_now(num_days) 
      @start_date + num_days * 24 * 60 * 60
    end 
end
TimeCalc.new.time_n_days_from_now(2)

example_6.rb

# The more indirect input comes, the more breakable the code is
def format_time
  format = ENV.fetch('TIME_FORMAT'){ %D %r } # To get Ruby env object, and sending #fetch to that object.
  Time.now.strftime(format)
end

format_time
 # => "06/24/13 01:59:12 AM"
 
ENV['TIME_FORMAT'] = '%FT%T%:z' 
format_time
# => "2013-06-24T01:59:12-04:00"
  

example_7.rb

# Yaml fetch version

require 'yaml'
def format_time
  prefs = YAML.load_file('time_pref.yml')
  format = prefs.fetch( %D %r ) { Time.now.strftime(format)
end
IO.write('time-prefs.yml', <<EOF) 
---
format: "%A, %B, %-d, at, %-I:%M %p"
EOF


format_time
 # => "Monday, June 24 at 2:07 AM"

example_8.rb

# More complicated 
require 'yaml'

def format_time
  user = ENV['USER']
  prefs = YAML.load_file("/home/#{user}/time-prefs.yml")
  format = prefs.fetch('format'){ '%D %r' }
  Time.now.strftime(format)
end

example_9.rb

#  input-collection stanza.
require 'yaml'

def format_time
  user = ENV['USER']
  prefs = YAML.load_file("/home/#{user}/time-prefs.yml")
  format = prefs.fetch('format'){ '%D %r' }
  
  Time.now.strftime(format) #  Let's emphasize this delineation with some added whitespace.
end