Which ruby style is preferred? [closed]

Question

option 1

data = 
  if page <= total_pages
    collection[((page - 1) * limit)...(page * limit)]
  else
    []
  end

option 2

data = []
if page <= total_pages
  data = collection[((page - 1) * limit)...(page * limit)]
end

option 3

if page <= total_pages
  data = collection[((page - 1) * limit)...(page * limit)]
else
  data = []
end

option 4

data = collection[((page - 1) * limit)...(page * limit)] || []

I personally prefer option 1, but, unfortunately, it doesn't look as nice. I was just wondering if this was addressed in some ruby style guide.

Answer 1

• Option1. That's the one I'd use, although I usually prefer a different layout:

  data = if page <= total_pages
    collection[((page - 1) * limit)...(page * limit)]
  else
    []
  end
  

• Option2: I'd strongly advise against it. When you write x = 1 in math you don't expect x to change its value afterwards, do you? the same applies when writing software (aka functional programming). This way the code becomes more clear.

• Option3: Not bad, though if is an expression in Ruby, no need to use it as a statement (problems: 1) you repeat the variable name, 2) you have to inspect each branch to see what's been done)

• Option4: it's orthogonal to your question. If you can write it, cleanly, as a one-liner without a conditional, do it. Here IMO it's on the edge, the expression is a bit too complicated.

• Option5: the obvious, if it fits in one line, use condition ? value_true : value_false.

Answer 2

There's also

data = page > total_pages ? [] : collection[((page - 1) * limit)...(page * limit)]

... which I think I'd prefer. It's just option 1 as a ternary, but still.

Or, you could toss it in a method, and do

return [] if page > total_pages
collection[((page - 1) * limit)...(page * limit)]

Otherwise I'd probably say option 3, for it's readability and straightforwardness.

Lastly, as in your option 4, an out-of-bounds range will return nil. You could just let that nil happen. If page is larger than total_pages it seems appropriate enough.