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December 20, 2015 22:19
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NullObject logger
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Purchase = Struct.new(:description, :price) | |
DATA = [ | |
Purchase.new("Walkman", "1.25"), | |
Purchase.new("Mini-disc player", "2.57"), | |
Purchase.new("Record player", "3.54") | |
] | |
require 'logger' | |
class TransactionImport | |
attr_reader :data, :logger | |
def initialize(data, options = {}) | |
@data = data | |
@logger = options.fetch(:logger) { default_logger } | |
end | |
def import | |
data.each do |record| | |
# ...do import work | |
logger.info("Processing #{record.description}") | |
end | |
end | |
private | |
def default_logger | |
@logger ||= Logger.new(STDOUT) | |
end | |
end | |
class FabulousLogger | |
def info(log_message) | |
puts ">>> #{log_message} <<<" | |
end | |
end | |
class NullObject < BasicObject | |
def method_missing(*) | |
end | |
def respond_to_missing?(name) | |
true | |
end | |
end | |
# Normal logger | |
TransactionImport.new(DATA).import | |
# An alternative logger | |
TransactionImport.new(DATA, logger: FabulousLogger.new).import | |
# No logging using `NullObject` | |
TransactionImport.new(DATA, logger: NullObject.new).import |
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