One line if statement not working

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遥遥无期
遥遥无期 2021-01-29 18:59
<%if @item.rigged %>Yes<%else%>No<%end%>

I was thinking of something like this?

if @item.rigged ? \"Yes\" : \"No\" 
<         


        
8条回答
  •  旧时难觅i
    2021-01-29 19:44

    In Ruby, the condition and the then part of an if expression must be separated by either an expression separator (i.e. ; or a newline) or the then keyword.

    So, all of these would work:

    if @item.rigged then 'Yes' else 'No' end
    
    if @item.rigged; 'Yes' else 'No' end
    
    if @item.rigged
      'Yes' else 'No' end
    

    There is also a conditional operator in Ruby, but that is completely unnecessary. The conditional operator is needed in C, because it is an operator: in C, if is a statement and thus cannot return a value, so if you want to return a value, you need to use something which can return a value. And the only things in C that can return a value are functions and operators, and since it is impossible to make if a function in C, you need an operator.

    In Ruby, however, if is an expression. In fact, everything is an expression in Ruby, so it already can return a value. There is no need for the conditional operator to even exist, let alone use it.

    BTW: it is customary to name methods which are used to ask a question with a question mark at the end, like this:

    @item.rigged?
    

    This shows another problem with using the conditional operator in Ruby:

    @item.rigged? ? 'Yes' : 'No'
    

    It's simply hard to read with the multiple question marks that close to each other.

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