Flutter function declaration

Named optional parameters You can call getHttpUrl with or without the third parameter. You must use the parameter name when calling the function . You can specify multiple named parameters for a function: getHttpUrl(String server, String path, {int port = 80, int numRetries = 3}) { // … }

A function can take parameters which are just values you supply to the function so that the function can do something utilising those values. These parameters are just like variables except that the values of these variables are defined when we call the function and are not assigned values within the function itself.

Navigating between the various routes(ie, pages) of an application in Flutter is done with the use of Navigator. The Navigator uses a common identifier to transition between routes. One can pass arguments to these routes using the arguments parameter of Navigator .

Dart function as parameter A Dart function can be passed to other functions as a parameter. Such a function is called a higher-order function. In the example, the apply function takes the inc and dec functions as parameters. We specify that the second parameter is a function type.

Dart: How to pass a function into a function (using a Function as a method parameter)