Is using the ternary operator like this considered less readable?

Question

I often like to do things like this:

return (aCondition == aThing)
        ? someLongExpression.getAThing()
        : somethingElse;

Is this practice considered more or less readable than using a simple if/else block, like this:

if (aCondition == aThing)
    return someLongExpression.getAThing();
else
    return somethingElse;

Answer 1

I find that the ternary operator (or conditional operator, as it's officially known in C#) can be used for improvement or abused horribly. So, employing a stock answer to many programming questions like this, it depends.

I generally think that fewer lines of code, if done right, minimizes the points of failure that could occur. One return statement in one line of code versus two returns embedded in an if-else-control block.

Now, without more context around your example, it's hard to say whether you're using it in its intended spirit or not. I'm inclined to say "yes" it's good and is more readable over the alternative given what I see.

Answer 2

If the content of the ternary operator doesn't get too long, I find it often more readable than if else. And in your example you have one return instead of two, which enhances readability.

There is an important difference between if else and the ternary operatator: Only the latter returns a value. This allows to use it on places where you can't use if else, and to reduce code repetition. In some cases, e.g. in the super-call of a constructor or an assignment to a static class variable, the alternatives are awkward.

One idiom I use sometimes, but which I never saw in other code is something like

(user.wantsEmail() 
  ? getEmailProvider() 
  : getMailProvider()
).send(message);  

Answer 3

You've defeated the purpose of that operator - to increase readability! You've taken a syntax designed to reduce code to one line and used it in place of a construct designed for multiple lines.

The only time you should use the ternary operator is when there is zero chance of any new options being added later. What if you later change it to return something different for greater than, less than, and equals? Or what if you want to add another operation after you do somethingElse?

Here's a case where ternary is perfect:

String msg = "You won " + results.size() + item + (results.size() > 1? "s": "") + ".";

Inline, this replaces a good 5-6 lines of code.

Side note: don't ever do something like this. Your successors will curse you.

return ((a==b)?(g==c?true:false):something();

Answer 4

I think the ternary operator is fine to use in that case. It's an if-else simplified by using a single return keyword. If the condition is long you can use a boolean variable to store it, and I prefer to format ternary statements like this:

return isConditionTrue ? someLongExpression.getAThing()
                       : somethingElse;

This also works well for when you have multiple conditions.

Answer 5

No, it is not bad practice.

Addendum:

[opinion]

Not everyone is onboard with this, but since the ternary operator is chainable and allows you to put condition and result side-by-side in a ceremony-free manner, I really like using it as follows.

return (aCondition == aThing)    ? someLongExpression.getAThing() :
       (aCondtion == otherThing) ? somethingElse.DoThis() :
       (oneMore == comparison)   ? somethingElse.DoThisThen() :
                                 : somethingElse;

It's not quite as clean as maps in functional languages, but it's similarish looking.

Though I think everyone can agree that at some point you get enough conditions that you should use an appropriate design pattern.

Edit: As pointed out in the comments, the above code is actually a really poor example of a time when this pattern makes sense. A better example is

return (customer.Country == "USA")   ? usa.ShippingFor(customer) :
       (customer.Region == "Europe") ? germany.ShippingFor(customer) :
                                     : NotAvailableShipping.Instance;

As always, this is not a replacement for appropriate design patterns. For example, if the above code had any need to get any more complex I would consider refactoring to a strategy pattern.

[/opinion]

Answer 6

It is not just about size.

The ternary operator is an expression (the 3 parts should be expressions, Condition a Boolean expression, the other two should be of the same type as each other). The type of the ternary expression is the same type as other two expressions.

S = AValue if Condition else AnotherValue

More generally, Condition, AValue, AnotherValue, S are expressions, Condition, AValue, AnotherValue are r-values, S is an l-value, AValue must conform to S, AnotherValue must conform to S, Condition must be Boolean.

If Then Else is procedural, it should do something. (often referred to as side effects, in the C tradition, where everything is a Function).

if Condition then do Something else do SomethingElse end  

If you understand this then the version using ternary is much easier to reason.

Examples shown in generic, human readable, pseudo code (any resemblance to other languages is purely coincidental).

Answer 7

Lets break this down into simple questions...

Q: Why was the ternary operator introduced?
A: To provide developers with an easy way to express simple if/else statements on a single line.

Q: When should I use the ternary operator?
A: It should be used when you have a simple if/else statement that makes more sense expressed in a single line.

Q: When should the ternary operator not be used?
A: If you plan on writing the statement over multiple lines just use an if/else statement since you are in essence defeating the whole point of the ternary operator. It should also be avoided if you plan to nest multiple ternary operators together since it was never intended to replace if/elseif statements. (FYI: to me this is a cardinal sin!)

I know a lot of the posts in this thread disagree with my statements but I fell that following my advice will produce the most readable and easy to follow code.