What is the difference between named and positional parameters in Dart

Question

Dart supports both named optional parameters and positional optional parameters. What are the differences between the two?

Also, how can you tell if an optional parameter was actually specified?

Answer 1

In Dart, positional parameters are specified by their position in the parameter list, while named parameters are identified by a name.

The main differences between the two are:

• Positional parameters must be passed in the same order as they appear in the function signature, whereas named parameters can be passed in any order.
• Positional parameters are defined by their position in the parameter list, whereas named parameters are defined by their name.
• Named parameters are optional by default and are enclosed in curly braces ({}) in the function signature, whereas positional parameters are optional when they have a default value and are enclosed in square brackets ([]) in the function signature.

To tell if an optional parameter was specified or not, you can use the null value. If an optional parameter has not been specified, its value will be null. You can also use the required keyword to indicate that a named parameter is required and must be provided by the caller. If a required named parameter is not provided, an error will be thrown at runtime.