Programming preference - use else ifs with multiple return statements? [closed]

Answer 1

For a simple if statement without too many lines of code having multiple returns is no problem. However, nothing infuriates me quite so much as:

function doTemperatureCalculations(double temperature) {
  if (temperature < 20) {
    /* 
      Gazillion lines of code here .....
     */
    return "Very cold!";
  } else if (temperature < 40) {
    /*
      Another gazillion loc .....
     */
    return "Summer in the North Pole.";
  } else {
    /*
      Multiple returns embedded throughout ....
     */
  }
}

Answer 2

Some would say that multiples return would be the problem here. But it's not really my point.

For my point of view, the if/else if is really important, because even if in your case you return some value, removing the elses would mean that you wouldn't put them anyway, and that would mean a totally different thing if the returns were not here.

Plus, imagine someday someone want to edit your code, and clean it up for a single return, this person could misunderstand your code and do a grave mistake like this :

public String getTemperatureMessage(double temp){
    String message;
    if(temp < 32)
        message = "Freezing";
    if(temp < 60)
        message = "Brr";
    if(temp < 80)
        message = "Comfortable";
    else 
        message = "Too hot";
    return message;
}

To clarify my point of view, keep the elses, it keep your code clear.

Answer 3

The only feasible alternative in this particular case is to grab the conditional operator ?:.

public String getTemperatureMessage(double temp) {
    return temp < 32 ? "Freezing"
         : temp < 60 ? "Brr"
         : temp < 80 ? "Comfortable"
         : "Too hot";
}

Left behind the question how that's readable to starters.

References

• JLS 15.25 Conditional Operator ?:
  • The operator is right-associative, thus such nesting of the operator will work "as expected"

Related questions

• To ternary or not to ternary?

Answer 4

Personally, I think the elses are unnecessary. Since this question is tagged as [language-agnostic], I'm going to provide a couple of examples of how I would write it:

def temperature_message(temp)
  return 'Freezing'    if temp < 32
  return 'Brr'         if temp < 60
  return 'Comfortable' if temp < 80
  'Too hot'
end

This is typical guard clause style, which both I personally and the Ruby community in general use quite often.

def temperature_message(temp)
  case
  when temp < 32
    'Freezing'
  when temp < 60
    'Brr'
  when temp < 80
    'Comfortable'
  else
    'Too hot'
  end
end

This is a typical switch as you would find it in some less powerful languages. This is probably one that I would not use, I would refactor it like this:

def temperature_message(temp)
  case temp
  when (-1.0/0.0)...32
    'Freezing'
  when 32...60
    'Brr'
  when 60...80
    'Comfortable'
  else
    'Too hot'
  end
end

Although I must admit I still find the first one easiest to read.

Since this is basically a mapping table, I would try to format it as such, so that everybody who reads the code, immediately sees the "table-ness":

def temperature_message(temp)
  case temp
  when (-1.0/0.0)...32 then 'Freezing'
  when         32...60 then 'Brr'
  when         60...80 then 'Comfortable'
                      else 'Too hot'
  end
end

This also applies to your original Java implementation:

public String getTemperatureMessage(double temp) {
    if(temp < 32) return "Freezing";
    if(temp < 60) return "Brr";
    if(temp < 80) return "Comfortable";
    else          return "Too hot";
}

Of course, since it is basically a mapping table, you might just as well implement it as a map:

def temperature_message(temp)
  {
    (-1.0/0.0)...32       => 'Freezing',
            32...60       => 'Brr',
            60...80       => 'Comfortable',
            80..(1.0/0.0) => 'Too hot'
  }.detect {|range, _| range.include?(temp) }.last
end

Answer 5

For simple 1-liners I tend to leave out the else but if there's more complex if blocks I tend to prefer the else to make it clear that the conditions are mutually exclusive.

Answer 6

I agree that the elses makes it more clear. The final else especially helps to make a visual distinction between the case where every branch has a return, and the cases where only some branches have a return (which could be a smell).