颤振/飞镖中工厂方法的目的是什么？

Question

I'm following a book that uses a factory method to implement a class that is a singleton.

I understand that the main purpose of this is to have just one instance of the class; But what exactly the keyword "factory" does in flutter?

This is the piece of code that I'm referring:

static final DbHelper _dbHelper = DbHelper._internal();

DbHelper._internal();

factory DbHelper() => _dbHelper;

I supose that the _dbHelper is the single instance that is being create with the _internal named constructor and that the factory method returns this single instance, is that correct? Am I missing something?

Answer 1

You have it correct!

You can read more about factory constructors here: https://dart.dev/guides/language/language-tour#factory-constructors