Safe navigation operator
In computer programming, the Safe navigation operator ?. (also known as Optional chaining operator, Safe call operator, Null-conditional operator) is an operator which is used to avoid sequental null checks and assignments and replace them with method/property chaining. It is currently supported in languages such as Groovy[1], Swift[2], Ruby [3], C#[4], Kotlin[5] and others.
There's currently no common naming convention for this operator.
The main advantage of using this operator is that it solves problem commonly known as Pyramid of doom. Instead of writing multiple nested ifs programmer can just use usual chaining, but put question mark symbols before dots (or other characters used for chaining).
Examples
Groovy
Null-safe operator:
def name = article?.author?.name
Swift
Optional chaining operator:
let name = article?.author?.name
Ruby
Ruby supports different &. safe navigation operator since version 2.3.0:
name = article$.author&.name
C#
In C# 6.0 and above, basic null-conditional operators .? and ?[]:
String? name = articles?[0].author?.name
Kotlin
Safe call operator:
val name = article?.author?.name
- ^ "6.1. Safe navigation operator". Retrieved 2016-01-28.
- ^ "Optional Chaining". Retrieved 2016-01-28.
- ^ "Ruby 2.3.0 Released". Retrieved 2016-01-28.
- ^ "Null-conditional Operators (C# and Visual Basic)". Retrieved 2016-01-28.
- ^ "Null Safety". Retrieved 2016-01-28.