Proc和Lambda的区别

Proc和Lambda的区别在网上没找到能说明白的文字

写写我自己的理解吧以免得忘记了还要再想

D:\>qri Proc
------------------------------------------------------------ Class: Proc
     +Proc+ objects are blocks of code that have been bound to a set of
     local variables. Once bound, the code may be called in different
     contexts and still access those variables.

D:\>qri lambda
---------------------------------------------------------- Kernel#lambda
     proc   { |...| block }  => a_proc
     lambda { |...| block }  => a_proc
------------------------------------------------------------------------
     Equivalent to +Proc.new+, except the resulting Proc objects check
     the number of parameters passed when called.

Proc和lambd都相当于定义一个代码块，然后这个代码块可以在需要用到的时候通过call(x,y,*z)来唤醒，但是他们的区别在于Proc中的代码影响到当前调用它的方法，而lambd中的代码只会在自己的代码块中起作用，如下一个广为传播的例子能够解释，我这里引用一下.

def foo
 f = Proc.new { return "return from foo from inside proc" }
 puts f.call #call的时候已经执行了return,所以foo方法执行完毕
 return "return from foo"#不会执行到这一句
end

def bar
 f = lambda { return "return from lambda" ;puts "continue?"}
 puts f.call #return只在(lambda)f这个块中返回，它后面这句puts "continue?"不会执行到
 return "return from bar"#这句话还会执行到，因为lambda中的return并没有影响到bar方法
end

puts foo 

输出

return from foo from inside proc

puts bar

输出

return from lambda
return from bar