这期内容当中小编将会给大家带来有关Ruby元编程的代码块怎么写，文章内容丰富且以专业的角度为大家分析和叙述，阅读完这篇文章希望大家可以有所收获。
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闭包
2.0.0p247 :133 > def my_method
2.0.0p247 :134?> x="GoodBye"
2.0.0p247 :135?> yield("cruel")
2.0.0p247 :136?> end
=> nil
2.0.0p247 :137 > x = "Hello"
=> "Hello"
2.0.0p247 :138 > my_method {|y| "#{x}, #{y} world"}
=> "Hello, cruel world"
2.0.0p247 :139 >作用域
块作用域 作用域门
2.0.0p247 :139 > v1 =1
=> 1
2.0.0p247 :140 > class MyClass
2.0.0p247 :141?> v2 =2
2.0.0p247 :142?> local_variables
2.0.0p247 :143?> def my_method
2.0.0p247 :144?> v3 =3
2.0.0p247 :145?> local_variables
2.0.0p247 :146?> end
2.0.0p247 :147?> local_variables
2.0.0p247 :148?> end
=> [:v2]
2.0.0p247 :149 > obj = MyClass.new
=> #
2.0.0p247 :150 > obj.my_method
=> [:v3]
2.0.0p247 :151 > obj.my_method
=> [:v3]
2.0.0p247 :152 > local_variables
=> [:v1, :x, :p, :obj, :a, :_]
2.0.0p247 :153 >
扁平化作用域
2.0.0p247 :156 > MyClass = Class.new do
2.0.0p247 :157 > puts "#{my_var} in the class definition"
2.0.0p247 :158?> define_method :my_method do
2.0.0p247 :159 > puts "#{my_var} in the method"
2.0.0p247 :160?> end
2.0.0p247 :161?> end
Success in the class definition
(irb):156: warning: already initialized constant MyClass
(irb):9: warning: previous definition of MyClass was here
=> MyClass
2.0.0p247 :162 > MyClass.new.my_method
Success in the method
=> nil
2.0.0p247 :163 >共享作用域
2.0.0p247 :178 > def define_methods
2.0.0p247 :179?> shared = 0
2.0.0p247 :180?> Kernel.send :define_method, :course do
2.0.0p247 :181 > shared
2.0.0p247 :182?> end
2.0.0p247 :183?> Kernel.send :define_method, :inc do |x|
2.0.0p247 :184 > shared += x
2.0.0p247 :185?> end
2.0.0p247 :186?> end
obj.instance_eval
2.0.0p247 :193 > class MyClass
2.0.0p247 :194?> def initialize
2.0.0p247 :195?> @v = 1
2.0.0p247 :196?> end
2.0.0p247 :197?> end
=> nil
2.0.0p247 :198 > obj = MyClass.new
=> #
2.0.0p247 :199 > obj.instance_eval do
2.0.0p247 :200 > self
2.0.0p247 :201?> @v
2.0.0p247 :202?> end
=> 1
2.0.0p247 :203 > v = 2
=> 2
2.0.0p247 :204 > obj.instance_eval {@v = v}
=> 2
2.0.0p247 :205 > obj.instance_eval {@v}
=> 2
2.0.0p247 :206 >
C.new.instance_exec(3)
2.0.0p247 :206 > class C
2.0.0p247 :207?> def initialize
2.0.0p247 :208?> @x,@y = 1,2
2.0.0p247 :209?> end
2.0.0p247 :210?> end
=> nil
2.0.0p247 :211 > C.new.instance_exec(3) {|arg| (@x + @y) * arg}
=> 9
2.0.0p247 :212 >净结室
2.0.0p247 :215 > class CleanRoom
2.0.0p247 :216?> def complex_calculation
2.0.0p247 :217?> p 'complex_calculation'
2.0.0p247 :218?> end
2.0.0p247 :219?> def
2.0.0p247 :220 > do_something
2.0.0p247 :221?> end
2.0.0p247 :222?> end
=> nil
2.0.0p247 :223 > clean = CleanRoom.new
=> #
2.0.0p247 :224 > clean.instance_eval do
2.0.0p247 :225 > if complex_calculation > 10
2.0.0p247 :226?> do_something
2.0.0p247 :227?> end
2.0.0p247 :228?> end
可调用对象
2.0.0p247 :235 > inc = Proc.new {|x| x*2}
=> #
2.0.0p247 :236 > inc.call(2)
=> 4
2.0.0p247 :237 >
2.0.0p247 :238 > dec = lambda {|x| x-1}
=> #
2.0.0p247 :239 > dec.class
=> Proc
2.0.0p247 :240 > dec.call(2)
=> 1
2.0.0p247 :241 >&操作符
2.0.0p247 :242 > def math(a,b)
2.0.0p247 :243?> yield(a,b)
2.0.0p247 :244?> end
=> nil
2.0.0p247 :245 > def teach_math(a,b,&operation)
2.0.0p247 :246?> puts "Let's do the math:"
2.0.0p247 :247?> puts math(a,b,&operation)
2.0.0p247 :248?> end
=> nil
2.0.0p247 :249 > teach_math(3,4){|x,y| x * y}
Let's do the math:
12
=> nil
2.0.0p247 :250 >2.0.0p247 :251 > def my_method(&the_proc)
2.0.0p247 :252?> the_proc
2.0.0p247 :253?> end
=> nil
2.0.0p247 :254 > p = my_method{ |name| "Hello, #{name}"}
=> #
2.0.0p247 :255 > p.class
=> Proc
2.0.0p247 :256 > p.call("BIll")
=> "Hello, BIll"
2.0.0p247 :257 >2.0.0p247 :262 > my_proc = proc{"Bill"}
=> #
2.0.0p247 :263 > my_method("hello",&my_proc)
hello the , Bill
=> nil
2.0.0p247 :264 >proc 和 lambda 对比 一般优先使用 lambda
2.0.0p247 :274 > def double(obj)
2.0.0p247 :275?> obj.call * 2
2.0.0p247 :276?> end
=> nil
2.0.0p247 :277 > l = lambda { return 10 }
=> #
2.0.0p247 :278 > double(l)
=> 20
2.0.0p247 :279 >
2.0.0p247 :280 > def another_dou
2.0.0p247 :281?> p = Proc.new { return 10}
2.0.0p247 :282?> result = p.call
2.0.0p247 :283?> return result * 2
2.0.0p247 :284?> end
=> nil
2.0.0p247 :285 > another_dou
=> 10
2.0.0p247 :286 >同样效果在 Ruby 1.9 中之后
2.0.0p247 :288 > p = -> { x + 1 }
=> #
2.0.0p247 :289 > p2 = lambda {|x| x + 1}
=> #
2.0.0p247 :290 >重访方法
2.0.0p247 :304 > obj = MyClass.new(1)
=> #
2.0.0p247 :305 > m = obj.method :my_method
=> #
2.0.0p247 :306 > m.call
=> 1
2.0.0p247 :307 >
2.0.0p247 :308 >
2.0.0p247 :309 > unbound = m.unbind
=> #
2.0.0p247 :310 > ano = MyClass.new(2)
=> #
2.0.0p247 :311 > m = unbound.bind(ano)
=> #
2.0.0p247 :312 > m.call
=> 2
2.0.0p247 :313 >
上述就是小编为大家分享的Ruby元编程的代码块怎么写了，如果刚好有类似的疑惑，不妨参照上述分析进行理解。如果想知道更多相关知识，欢迎关注创新互联行业资讯频道。
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