Factories vs Builder functions about mobx.dart

[pavanpodila]

Wow this is beautiful. Love it. I definitely have to dig deeper into source_gen and understand its capabilities. From the looks, it is very promising and opens up a world of possibilities with some meta-programming wizardry.

Thanks for sharing a detailed example 💯

[pavanpodila]

Our API is already providing it: observable(10). For a factory the identifier would just become capitalized. Still not clear if a function or a factory-constructor is better. Since I am jaded by using MobX JavaScript, I am just leaning towards a function.

How about we provide both for now and see what sticks ??

[katis]

We can just keep the builder function, I don't see the point in providing two ways to do things.
Maybe in the future this whole point will be moot if we can create a code generator that does the same kind of magic as MobxJS annnotations. Then the use of builders would probably be rare any way.

[pavanpodila]

Let's go the Dart way with factories. Although the API is different in JS, I think we should take the Dart convention.

[pavanpodila]

We can just keep the builder function, I don't see the point in providing two ways to do things.
Maybe in the future this whole point will be moot if we can create a code generator that does the same kind of magic as MobxJS annnotations. Then the use of builders would probably be rare any way.

I am still curious how source_gen would help

[katis]

@pavanpodila sorry, missed your messages.

I think it should be possible to use source_gen to have code like this:

part 'view_model.g.dart';

abstract class ViewModel {
  factory ViewModel() = _$ViewModel;

  @observable
  int counter;

  @action
  void increment() {
    counter++;
  }
}

generate view_model.g.dart like this:

class _$ViewModel extends ViewModel {
  _$ViewModel() {
    _$increment = action(super.increment, name: 'ViewModel.increment');
  }
  
  final _$counter = observable(0); // not sure how to handle initial value yet
  int get counter => _$counter.value;
  set counter(int value) => _$counter.value = value;
  
  Action _$increment;
  @override
  void increment() {
    _$increment();
  }
}

Then you could easily use ViewModel in reactive situations:

final vm = ViewModel();
autorun(() {
  print(vm.counter);
});
vm.increment();
vm.increment();

built_value does this kind of magic to create immutable values classes.