Question

我有一个Builder类，可以让你添加一个实例变量：

class Builder
    def initialize
        @lines = []
    end

    def lines
        block_given? ? yield(self) : @lines
    end

    def add_line( text )
        @lines << text
    end
end

现在，我该如何更改

my_builder = Builder.new
my_builder.lines { |b|
    b.add_line "foo"
    b.add_line "bar"
}
p my_builder.lines # => ["foo", "bar"]

进入这个？

my_builder = Builder.new
my_builder.lines {
    add_line "foo"
    add_line "bar"
}
p my_builder.lines # => ["foo", "bar"]

Answer 1

class Builder
    def initialize
        @lines = []
    end

    def lines(&block)
        block_given? ? instance_eval(&block) : @lines
    end

    def add_line( text )
        @lines << text
    end
end

my_builder = Builder.new
my_builder.lines {
    add_line "foo"
    add_line "bar"
}
p my_builder.lines # => ["foo", "bar"]

Answer 2

您也可以使用ary的参数长度在ruby最佳实践中使用方法：

class Foo

attr_accessor :list

def initialize
   @list=[]
end

def bar(&blk)

  blk.arity>0 ? blk.call(self) : instance_eval(&blk)

end

端

X = Foo.new

x.bar做 list＆lt;＆lt; 1 list＆lt;＆lt; 2 list＆lt;＆lt; 3 端

x.bar do | foo | foo.list＆lt;＆lt; 4 foo.list＆lt;＆lt;五 foo.list＆lt;＆lt; 6 端

将x.list.inspect

放入

块内的实例评估

2 个答案: