Ruby：嵌套的 if 语句
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Ruby: nested if statements
提问by rlhh
I was writing some code and it ended up being way too ugly to my liking. Is there anyway that I can refactor it so that I don't use nested if statements?
我正在编写一些代码，但它最终变得太丑了，我不喜欢。无论如何，我可以重构它以便我不使用嵌套的 if 语句吗？
def hours_occupied(date)
#assuming date is a valid date object
availability = get_work_hours(date)
focus = "work"
if availability.nil
availability = get_family_hours(date)
focus = "family"
if availability.nil
availability = get_friend_hours(date)
focus = "friends"
end
end
end
I know I'll be able to do something like this for availability
我知道我可以为可用性做这样的事情
availability = get_work_hours(date) || get_family_hours(date) || get_friend_hours(date)
but how do I set the focus variable accordingly?
但是如何相应地设置焦点变量？
采纳答案by trushkevich
One more way is just to reassign values if there is a need:
另一种方法是在需要时重新分配值：
def hours_occupied(date)
availability, focus = get_work_hours(date), "work"
availability, focus = get_family_hours(date), "family" unless availability
availability, focus = get_friend_hours(date), "friend" unless availability
end
or using an iterator:
或使用迭代器：
def hours_occupied(date)
availability = focus = nil
%w(work family friend).each {|type| availability, focus = self.send(:"get_#{type}_hours", date), type unless availability}
end
回答by Don Cruickshank
I would do something like the following as it makes it clear that each case is mutually exclusive:
我会做类似以下的事情，因为它清楚地表明每种情况都是相互排斥的：
def hours_occupied(date)
if availability = get_work_hours(date)
focus = "work"
elsif availability = get_family_hours(date)
focus = "family"
elsif availability = get_friend_hours(date)
focus = "friends"
end
end
回答by tokland
I'd write:
我会写：
def hours_occupied(date)
focus = if (availability = get_work_hours(date))
"work"
elsif (availability = get_family_hours(date))
"family"
elsif (availability = get_friend_hours(date))
"friends"
end
# I guess there is more code here that uses availability and focus.
end
However, I am not sure having different methods for different types is a good idea, it makes code harder to write. A different approach using Enumerable#map_detect:
但是，我不确定为不同的类型使用不同的方法是个好主意，它会使代码更难编写。使用Enumerable#map_detect 的不同方法：
focus, availability = [:work, :family, :friends].map_detect do |type|
availability = get_hours(date, type)
availability ? [type, availability] : nil
end
回答by steenslag
A case whenis also an option:
一种情况 when也是一种选择：
focus = case availability
when get_work_hours(date)
"work"
when get_family_hours(date)
"family"
when get_friend_hours(date)
"friends"
end
