Dart - declare function as variable

Question

In Dart - as in many other languages - there is more than one way to declare a function. The question is, are there any differences aka "when should I use which"?

void foo(int i) {
  print('i = $i');
}

void main() {
  void Function(int) bar = (int j) {
    print('j = $j');
  };

  foo(1);
  bar(2);
}

Is there any difference in the declaration of foo or bar other than the fact that bar can be overwritten?

Answer 1

Functions can be introduced by

• function declarations
• method decla-rations
• getter declarations
• setter declarations
• constructor declarations
• function literals

In terms of Dart specification there is 2 differences between function literals (aka anonymous function) and other declarations

1. it has no name - anonymous
2. we can't declare a return type (which only obtained by means of type inference)

If you prefer to keep type safety, you will have to write long declaration.

Consider this example:

String foo(int i, {bool b}) => '$b $i'; // return type declared

final bar = (int i, {bool b}) => '$b $i'; // return type could not be infered

final String Function(int i, {bool b}) bar = (i, {b}) => '$b $i'; // return type infered

From my perspective

1. bar isn't as readable as foo declaration
2. Let functions literals do their anonymous job =)

PS If I missed anything - please edit my answer or reach me in comments