build VS freezed

The official documentation is here. It's not very beginner friendly. Therefore, it might be easier to look at the examples.

In the first part of this series of posts, we discussed how Flutter and -Dart in general- makes use of builders to generate source code during the build process.

build: "Defines the basic pieces of how a build happens and how they interact."

build_runner

Having spent about 6 months each with SwiftUI and Flutter I vastly prefer working with Flutter. Swift is a far more ambitious language but really doesn't live up to it's own marketing. Many of the features are half down (generics and protocols are both full of holes). Dart on the other hand doesn't have half as many nice features but the one's that are there are rock solid. Reified generics in particular is far nicer to work with (Swift's compiler gets regularly gets lost on type resolution and then doesn't give you any way to give it hints). Dart also seems to be heading in the right direction. It's added null safety and the upcoming metaprogramming features should fill in many of the gaps that are currently filled by the very practical but clunky https://pub.dev/packages/build.

I am one of the authors of the build package (https://github.com/dart-lang/build) which does effectively expose a plugin system. We take the approach of creating a wrapper script that actually just generates the real program (adds imports to the plugins, registers them, etc) and then it just runs that program. There are several downsides to this approach though (primarily, slow startup).

There is the `sealed` class modifier which allows for exhaustive matching on possible types: https://dart.dev/language/class-modifiers#sealed

There's also a package called freezed which offers similar utility (you might already be familiar with this seeing as you mentioned pattern matching): https://pub.dev/packages/freezed

I recall there being a reason unions aren't generally implemented, though I'm not sure where I read it. It was to do with union types being unnecessarily complex for the compiler and the code they tend to produce, at no real benefit to the programmer or the resulting program. Go's lack of unions is essentially based around the same reasoning.

Interesting. May I ask how this differs from something like Freezed https://pub.dev/packages/freezed and its from/ToJson features ? I haven't used it yet, but I'm just curious about the concept and use of these sort of packages.

The official site does show what you can use it for but to explain a bit more, it helps you work faster.

One rather minor suggestion: it took me a while to understand exactly what the benefits were, but the example shown on this page of the docs summarized it well. I would suggest showing an example like that at the top of the main Readme and first page of the site, before or right after the motivation section, similar to how Freezed immediately shows its value proposition.

Read more on what you can do with Freezed.

freezed on pub.dev

We use freezed for our models, and then use withConverter in the firestore SDK to easily translate between firestore and our models... however we run into issues with concurrent updates to documents.

Once the package has been created, we will install freezed for JSON serialization and value equality , as this library provides helpful tools for these tasks. We will use json_serializable for JSON serialization. To install freezed and freezed_annotation, open your terminal inside the models package and use the command:

Data class: freezed

I've recently been exploring a codebase which is heavily using Freezed with Bloc. The resulting code base is almost an entirely different language altogether, and comes with almost triple the files of a non-freezed codebase.