withers_extension 0.9.0

Uses class_extensions to generate withers. Withers are a convenient way of constructing copies of immutable objects with altered values.

Description

Uses class_extensions to generate withers. Withers are a convenient way of constructing copies of immutable objects with altered values.

See also to_string_extension, json_extension

Tutorial

1. We need a class to generate withers for. You usually want to generate withers for immutable classes.

   ${PROJECT_ROOT}/lib/model.dart

   import 'package:meta/meta.dart';
      
   @immutable
   class SomeValueClass {
     final String strVal;
     final int intVal;
   }
   

2. For withers to work you need to add some boiler plate:

   • part 'model.g.dart';
   • annotation @Withers()
   • mixin _$SomeValueClass
   • all args constructor SomeValueClass(this.strVal, this.intVal);

   ${PROJECT_ROOT}/lib/model.dart

   import 'package:meta/meta.dart';
   import 'package:withers_extension_annotations/annotations.dart';
      
   part 'model.g.dart';
      
   @Withers()
   @immutable
   class SomeValueClass with _$SomeValueClass {
     final String strVal;
     final int intVal;
      
     SomeValueClass(this.strVal, this.intVal);
   }
   

3. Configure code generation. More info at build.

   ${PROJECT_ROOT}/build.yaml

   targets:
     $default:
       builders:
         class_extensions:
           generate_for:
           - lib/*.dart
   

4. Add dependencies.

   ${PROJECT_ROOT}/pubspec.yaml

   name: example
      
   dependencies:
     withers_extension_annotations: ^0.1.0
      
   dev_dependencies:
     build_runner: ^1.0.0
     withers_extension: 8.0.0
   

5. Run code generation: pub run build_runner build. File ${PROJECT_ROOT}/lib/model.g.dart should be created.

6. If everything goes well you should be able to use withers.

   ${PROJECT_ROOT}/bin/main.dart

   import 'package:example/model.dart';
      
   void main() {
     var some = SomeValueClass("some", 0);
     var other = some.withIntVal(1).withStrVal("other");
   }
   

7. You can also see the example.