第二个子句不需要 !variable.nil? 检查——如果评估达到那个点，variable.nil 肯定是错误的(因为短路).

The second clause does not need a !variable.nil? check—if evaluation reaches that point, variable.nil is guaranteed to be false (because of short-circuiting).

这应该足够了:

variable = id if variable.nil? || variable.empty?

如果您使用 Ruby on Rails，Object.blank? 解决了这个问题:

If you're working with Ruby on Rails, Object.blank? solves this exact problem:

如果对象为 false、空或空白字符串，则该对象为空.例如，""、" "、nil、[] 和 {}代码>都是空白的.

An object is blank if it’s false, empty, or a whitespace string. For example, "", " ", nil, [], and {} are all blank.