經常看到 rails 中有很多 config 的設定，像是 rspec 等等，會用一個 black 包起來就可以做設定了，那內部實作是如何?
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| module Mail
class Configuration
DEFAULT_VERSION = 'v1'
DEFAULT_API_KEY = 'token'
class << self
attr_writer :version, :api_key
def configure(&block)
yield self
self
end
def version
@version ||= DEFAULT_VERSION
end
def api_key
@api_key ||= DEFAULT_API_KEY
end
end
end
end
Mail::Configuration.configure do |config|
config.version = 1
config.api_key = 2
end
|
或是另外一種寫法
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| module Mail
module Config
extend self
attr_accessor :token
attr_accessor :logger
def reset
self.token = nil
self.logger = nil
end
reset
end
class << self
def configure
block_given? ? yield(Config) : Config
end
def config
Config
end
end
end
Mail.configure do |config|
config.token = ENV['MAIL_API_TOKEN']
config.logger = Logger.new(STDOUT)
config.logger.level = Logger::INFO
fail 'Missing ENV[MAIL_API_TOKEN]!' unless config.token
end
|