Differentiate between named parameters and positional parameters in Dart?

In Dart, there are two types of function parameters: named parameters and positional parameters. These parameter types allow you to define functions with different ways of passing arguments. The main difference between them lies in how you pass arguments to the function.

  1. Positional Parameters: Positional parameters are the most common and traditional way to define function parameters. When you use positional parameters, the order of the arguments matters, and you pass the values in the same order as the parameters are declared in the function signature.

Syntax:

ReturnType functionName(Type paramName1, Type paramName2, ...) {
  // Function body
}

Example using positional parameters:

void printDetails(String name, int age, String address) {
  print('Name: $name, Age: $age, Address: $address');
}

// Calling the function with positional arguments
printDetails('John', 30, 'New York');

In the example above, name, age, and address are positional parameters. When calling the function printDetails, you must provide the arguments in the exact order defined in the function signature.

  1. Named Parameters: Named parameters allow you to specify the parameter name when passing arguments to a function. The order of the arguments is not important, and you explicitly provide the parameter names followed by a colon (:) when calling the function.

Syntax:

ReturnType functionName({Type paramName1, Type paramName2, ...}) {
  // Function body
}

Example using named parameters:

void printDetails({String name, int age, String address}) {
  print('Name: $name, Age: $age, Address: $address');
}

// Calling the function with named arguments
printDetails(name: 'Alice', address: 'London', age: 25);

In the example above, name, age, and address are named parameters. When calling the function printDetails, you can specify the arguments by providing the parameter names along with their values, and the order of the arguments doesn’t matter.

Additional points to note:

  • You can use both positional and named parameters in the same function, but positional parameters must come before named parameters in the function signature.
  • You can provide default values to named parameters, making them optional when calling the function.
  • The use of named parameters often improves the readability of the function calls, especially when there are many optional parameters or when the function has default values for some parameters.

In summary, the main difference between named and positional parameters in Dart is in how you pass arguments to a function. Positional parameters rely on the order of arguments, while named parameters allow you to specify the parameter names when calling the function, making the code more expressive and less dependent on argument order.

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