What is the difference between Function() and Function in dart?

Question

While declaring a Function member in a class we can do both;

Function first;
Function() second;

What is the difference between them?

Solution

• Function represents any function:

void function() {}
int anotherFunction(int positional, {String named}) {}


Function example = function; // works
example = anotherFunction; // works too

• Function() represents a function with no parameter:

void function() {}
int anotherFunction(int positional, {String named}) {}


Function() example = function; // works
example = anotherFunction; // doesn't compile. anotherFunction has parameters

A variant of Function() could be:

void Function() example;

Similarly, we can specify parameters for our function:

void function() {}
int anotherFunction(int positional, {String named}) {}

int Function(int, {String named}) example;

example = function; // Doesn't work, function doesn't match the type defined
example = anotherFunction; // works