dataclass

Description:

dataclass

Welcome to the Macro version of Freezed!
It has been renamed to dataclass, for the sake of enabling users to
temporarily use both build_runner and macros.
This is a tool that generates toString, copyWith (including copyWith(field: null)), hashCode, ==
and more.
This is a very early proof of concept about what Freezed would look like when macros land in Dart.
Beware: Due to many missing Macro features, lots of Freezed features are
missing or broken. Use at your own risk :)
Installation #
To get started with the macro version of Freezed:


Make sure that you use a Dart version >= 3.5.0-dev


Enable macros in your analysis_options.yaml as followed:
# analysis_options.yaml
analyzer:
enable-experiment:
- macros
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Install Freezed >= 3.0.0:
name: your_app
environment:
sdk: ">=3.5.0-0.0-dev <4.0.0"

dependencies:
# Freezed is now a "dependencies".
# freezed_annotation is no-longer needed
dataclass: ^3.0.0-0.0.dev
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Usage #
Two possible syntaxes are supported:


Constructor-first.
You define a class with a constructor, and the macro will
generate fields for you.
This gives fine-grained control over positional vs named parameters.
It offers the ability to use asserts, super, ...
Although macros have still lots of things related to this that don't work.
So although the syntax is very flexible, lots of things are not supported yet.


Field-first.
You define a class with fields, and the macro will generate a constructor for you.
This is the most stable syntax.
But it is less flexible, and not very dart-like.
If you want full control over constructors, you'll have to use the constructor-first syntax.


Constructor-first usage #
To use the constructor-first syntax, define a class with a constructor,
but no fields:
@Data()
class Example {
Example({required int foo, required String bar});
}
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The macro will generate the fields for you, along with
the various methods.
void main() {
final example = Example(foo: 42, bar: '42');
print(example.foo); // 42
}
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Using named constructors.
Naturally, the macro expects that you use the default constructor.
If you wish to generate fields based on a named constructor instead,
specify @Data(constructor: '<constructor name>').
@Data(constructor: 'custom')
class Example {
Example.custom({required int foo, required String bar});
}
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Field-first usage #
To use the field-first syntax, define a class with fields
but default constructor.
The macro will then generate a constructor for you, along
with the various methods.
@Data()
class Example {
final int foo;
final String bar;
}
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Currently, all fields are "named" parameters, and they are optional if they are nullable.
void main() {
final example = Example(foo: 42, bar: '42');
print(example.foo); // 42
}
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Specifying the constructor name
If you wish to generate a non-default constructor,
you can specify @Data(constructor: '<constructor name>').
@Data(constructor: 'custom')
class Example {
final int foo;
}

void main() {
final example = Example.custom(foo: 42);
}
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Features #



features
status
comment




copyWith
✅



toString
✅



==/hashCode
✅



unions
🚧
Supported, but macros are a bit bugged with regards to class inheritance.


json support
🚧



default values
❌
Requires macros to be more developed


deep copy
❌
Requires macros to be more developed


generic classes
❌
Requires macros to be more developed