词汇：end
n. 结束；末端；目标；死亡；尽头
相关场景
- And I think that's very important . In a crisis situation, it's very very easy to blame others. Ah and invariably that ends up in a very divisive environment.>> A leader in crisis
- Generally speaking, high-end hotels may have a moderately equipped business center on one level and a nicely equipped one on the club or concierge level.
一般来说，高端酒店可能在一层有一个设备适中的商务中心，在俱乐部或礼宾层则有一个设施齐全的商务中心。>> 10. Business Center- 48.memoization优化模式:
- def current_user
@current_user ||= User.find(logged_in_user_id)；
def shipped?(order_id) @status ||= begin file = fetch_confirmation_file ; file? parse_confirmation_file(file) : {} end @status[order_id] == :shipped end
返回的是true or false； 而current_user 返回的是变异对象；如果不希望调用者修改缓存的变量，那应该考虑让被记忆化的方法返回冻结对象。>> Effective Ruby- 47.循环中的对象字面量:
- FATal_CODES = %w(F1 F2 F3).map(&:freeze).freeze; def fatal?(errors) errors.any? {|e| FATAL_CODES.include?(e.code)} end 将数组变成常量；减少对象的生成数量。>> Effective Ruby
- 39.测试的重要性； fuzzbert and mrproper属性测试；SimpleCov 测试覆盖率 ZenTest监测代码:
- 尽可能的自动化测试；运行代码才知道代码在干啥；测试又happy path and exception path; fuzz testing and property testing; require('fuzzbert') require('uri') fuzz('URI::HTTP:build') do data("random server names") do FuzzBert::Generators.random end deploy do |data| URI::HTTP.build(host: data, path: '/') end 会持续运行，手动停止。 MrProper； properties("Version") do data([Integer, Integer, Integer]); property("new(str).to_s == str") do |data| str= data.join('.'); assert_equal(str, Version.new(str).to_s)； 测试驱动开发里面的测试并不好写，>> Effective Ruby
- 38. Mock模拟对象 define一个method,并模仿mock需要调用的特定对象；:
- def alive? echo = Time.now.to_f.to_s response = get(echo) response.success? && response.body ==echo end; private get(echo) url=RUI::HTTP.build(host:@server, path: "/echo/#{echo}") HTTP.get(url.to_s) end
monitor = Monitor.new("example.com"); response = MiniTest::Mock.new ; monitor.define_singleton_method(:get) do |echo| response.expect(:success? , true); response.expect(body, echo); response end assert(monitor.alive?, "should be alive") response.verify end; 用Mock格里外部系统不稳定因素；Mock#verify>> Effective Ruby- 37. MiniTest的测试需求:
- unit testing or spec testing= behavioral specification; 在单元测试基础上封装而来。
describe("when comparing") do ... end before do ...end it("orders correctly") do ..end; before == setup; after = teardown; 如果喜欢需求测试风格，参考RSpec cucumber等。 MiniTest::Expectations>> Effective Ruby- 34.Proc:
- code block is a Proc; 弱Proc,参数可以不一致。强Proc参数数量严格一致。lambda 为强Proc.
func= ->(x) {"Hello #{x}} ; func.call("a","b") #ArgumentError: wrong number of arguments(2 for 1);
def test(&block) block.lambda? end;>> Effective Ruby- 32.猴子补丁Monkey Patching and refinement:
- Active Support的问题； module OnlySpace ONLY_SPACE_UNICODE_RE= %r/\A[[:space:]]*\z/
def self.only_space?(str) if str.ascii_only? !str.bytes.any {|b| !32 && !b.between?(9,13)} else ONLY_SPACE_UNICODE_RE === str end end
>> Effective Ruby- 31. eval; instance_eval定义的是单例方法；:
- def glass_case_of_emotion x="I'm in a " + __method__.to_s.tr('_',' ') binding; binding 可以获得当前的临时域并把这个临时域封装到Binding对象中作为返回结果。这个指定的上下文是eval方法的第二个参数； eval("x", glass_case_of_emotion); class_eval很像是重新打开类，实际上是被定义在Module里面，only被模块和类使用。= moudle_eval; instance_eval访问实例变量；class_eval定义实例方法。 class Widget attr_accessor(:name, :quantity) def initialize(&block) instance_eval(&block) if block end ;;; w= Widget.new do |widget| widget.name= "Elbow Grease" ; @quantity = 0; end ; instance_exec, class_exec, moudle_exec; only accept 代码块， no string； object.instance_eval("@#{name} = DEFAULT")
module Reset def self.reset_var (object, name) object.instance_exec("@#{name}.to_sym") do |var| const = self.class.const_get(:DEFAULT); instance_variable_set(var, const) end ...>> Effective Ruby- 30.define_method or method_missing:
- 如果没有找到任何方法，method_missing就会被执行；但是因为又super的原因，这里会有迷惑。def method_missing(name, *args, &block) if @hash.respond_to?(name) @hash.send(name, *args, &block) else super end end; Hash.public_instance_methods(false).each do |name| define_method(name) do |*args, &block| @hash.send(name, *args, &block) end; h.public_methods(false).sort.take(5); 实现了Hash的方法。
AuditDecorator @logger = Logger.new($stdout); private def method_messing(name, *arg, &block) @logger.info("calling '#{name}' on #{@object.inspect}"); @object.send(name, *args, &block); define_method更加适合做这个了。 mod=Module.new do object.public_methods.each do |name| define_method(name) do |*args, &block| @logger.info("") @object.send(name, *args, &block) end end end extend(mod) ; 创建了一个匿名的模块。 —— define_method恢复了内省方法。。 respond_to? and respond_to_missing?>> Effective Ruby- 28. 模块和类的钩子方法:
- Ruby的hook在类和模块的级别实现元编程。在类和模块中定义方法-单例方法。混合引入模块时，ruby都会调用钩子方法included or extended；这个钩子可以看作是一个，通知通知当前模块即将要被扩展到另一个类中。代理的方法只是重定向了。interited; method_added method_removed method_undefined 实例方法；singleton_method_added singleton_method_remove singleton_mothod_undefined 可以被用于模块方法或类方法。这些方法只接受一个symbol ,方法名； Triggers singleton_method_removed(:hello) class << self; remove_mothod(hello);end>> Effective Ruby
- 26. 限制retry次数,retry间隔指数增加:
- retries = 0; begin service.update(record); rescue VendorDeadlockError ; raise if retries >= 3 ; retries += 1; logger.warn("API failure: #{e}, retrying...");sleep(5 ** retries); retry; end
>> Effective Ruby- 25. ensure里面不要用return:
- 也不要用throw；一般不要在里面改变控制流，会抛弃异常。比如 begin 。raise。 ensure next; end>> Effective Ruby
- 24. block and ensure:
- 分配-使用-释放；file = File.open(file_name, 'w'_...file.close;因为又垃圾回收的原因，中途发生异常也会被回收资源，但是你不确定什么时候会被回收，所以你如果能及时处理，那更好。那么就算需要begin。。。ensure file.close if file end;也可以通过 File.open(file_name, 'w') do |file| ...end，这种block的方式。块执行晚后文件会被关闭。将资源管理简单化。 简单化的资源管理，也衍生出一个 传block给方法的问题，可以用class Lock def self.acquire ; lock =new ; lock.exclusive_lock!; if block_given? yield(lock) else lock # Act more like Lock::new. end ensure if block_given? # ...end end end; 没有绑定块时候，Lock::acquire 。。。； 类方法上使用块和ensure语句将资源管理的逻辑抽离出来。>> Effective Ruby
- 22. raise:
- raise("coffee machine low on water") => raise(RuntimeError, "coffee machine low on water")
异常的处理是基于类型的。Exception or StandardError ; class CoffeeTooWeakError < StandardError; end
raise(CoffeeTooWeakError, "coffee to water ratio too low")
super("invalid temperature: #@temperature") raise(TemperatureError.new(180))>> Effective Ruby- 21.对集合和核心类优先使用委托而非继承:
- is a，还是 has a， 委托就是有一个。。。require('forwardable'); class RaisingHash extend(Forwardable) include(Enumerable) def_delegators(@hash, :[], :[]=, :delete, :each, :keys, :values, :length, :empty?, :has_keys) end Forwardable模块让使用委托的过程变得容易。 del_delegator(@hash, :delete, :erase!)>> Effective Ruby
- 15.优先使用实例变量:
- @@开头的变量是类变量，bind在类上。； 单例模式；private_class_method(:new, :dup, :clone) def self.instance @@single ||= new; 其实类方法是一个假象，类方法实际上是一个类的对象的实例方法。Singleton模块作为Ruby标准库的一部分；require('singleton'); class Configuration include(Singleton) end;>> Effective Ruby
- that ends our special bulletin for today.
今天的特别报道到此结束。>> 76-April Fools' Day- It's almost the light at the end of the tunnel.>> 16. Slang in Tour Guiding
- All employees can get year-end bonus.>> 60-The Future
- You know you get your thoughts together, have a process in place for decision making. Don't allow yourself to become weaponized. Like at all you know or and don't have it to extend I have a temper. It works against you. You always have to end up apologizing.>> work hard but work smart
- Second, it came quickly, By the time Itomi and her family went back to Japan, at the end of the year her English was closing in on the way the other children in the neighborhood were talking.>> comprehensible input - One way only one way to acquire a language
- I think there's an echo on your end, maybe try using headphones.>> online meeting on online classes
- The children compete against each other to reach the other end of the pool.>> 94-Future Champions