Ruby做/结束vs括号 [英] Ruby do/end vs braces

问题描述

根据我使用花括号还是使用do/end，为什么此地图表达式会产生不同的结果?

Why does this map expression produce different results depending on whether I use braces or do/end?

a = [1,2,3,4,5]


p a.map { |n|
    n*2
}  
#=> [2,4,6,8,10]


p a.map do |n|
    n*2
end  
#=> [1,2,3,4,5]

推荐答案

这是因为第二行被解释为:

That's because the second line is interpreted as:

p(a.map) do ... end

代替:

p(a.map do ... end)

在这种情况下，语法是模棱两可的，do似乎没有像{那样牢固地绑定.

The grammar is ambiguous in this case and do doesn't seem to bind as strongly as {.

这篇关于Ruby做/结束vs括号的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！