Functions

A function allows you to call a code from a shorter one, and in this way allows you to reuse code.

Positional:

void name (String message, int lineNum) {
  // ...
}

name (String message, int lineNum) {
  return // ...
}

Calling the function:

name ('text', 55);

Named:

void name ({String message, int lineNum}) {
//...
}

name ({String message, int lineNum}) {
return //...
}

Calling the function:

name (message: 'A bug!', lineNum: 44);

https://flutterbyexample.com/lesson/function-arguments-default-optional-namedflutterbyexample.com