Flutter StatefulWidget State name collision

[torbenkeller]

Since today in my Android Studio the dart compiler values the dartz import more than the material.dart import so I have to use

import 'package:dartz/dartz.dart' as dz;

when I want to use a StatefulWidget and some dartz objects or functions. Otherwise the app doesn't compile and throws this error message:

Compiler message:
lib/main.dart:31:32: Error: Expected 0 type arguments.
class _HomeWidgetState extends State<HomeWidget> {
                               ^
lib/main.dart:28:20: Error: The return type of the method 'HomeWidget.createState' is '_HomeWidgetState', which does not match the return type, 'State<StatefulWidget>', of the overridden method, 'StatefulWidget.createState'.
 - '_HomeWidgetState' is from 'package:stock_check/main.dart' ('lib/main.dart').
 - 'State' is from 'package:flutter/src/widgets/framework.dart' ('/C:/src/flutter/packages/flutter/lib/src/widgets/framework.dart').
 - 'StatefulWidget' is from 'package:flutter/src/widgets/framework.dart' ('/C:/src/flutter/packages/flutter/lib/src/widgets/framework.dart').
Change to a subtype of 'State<StatefulWidget>'.
  _HomeWidgetState createState() => _HomeWidgetState();

[mateusfccp]

I don't see this as an issue.
This is the default behavior for name conflict between packages, and there's indeed a State monad in dartz.

If your problem is having to type dz. to use dartz (or whatever prefix you chose to import dartz as), you may instead import only what you need with show/hide, like:

// Will import the entire package except for State
import 'package:dartz/dartz.dart' hide State;

or

// Will import only the name Option from dartz, everything else won't be imported
import 'package:dartz/dartz.dart' show Option;

[spebbe]

As @mateusfccp (thanks!) mentions above, Dart comes with excellent tools for dealing with name conflicts.

While I agree that it is unfortunate that there is a conflict to begin with, the name State for the specific structure in dartz is so standardized that it would be very confusing to call it anything else.

Are you ok with closing this?

[torbenkeller]

@spebbe sure. I just wanted to open this so if somebody searches for this error he will find the solution.

[spebbe]

ah, ok!

[Peng-Qian]

personally, I think it would be nice if dartz could avoid the name conflicts since lots of flutter developers are using the nice plugin. 👍

It a little bit annoying to use a prefix or hide/show (prefix will cause the syntax longer and all of them need a manually fix for every import). 😁

[mateusfccp]

I don't think so. I hardly use StatefulWidgets, but even when I use, my logic is decoupled of my UI, so I won't use dartz and flutter/widgets in the same file.

[Peng-Qian]

You are absolutely right, UI should be decoupled of logic. The reason I suggest here is that if we apply dartz to value object (DDD), Either() will frequently appear to UI layer.