generic_enum_annotation 0.1.5

Generic Enum Annotation #

Build Status

Introduction #

This library defines annotation classes (with const constructor). These are used to annotate classes that extend generic_enum.

GenericEnum is a base class for creating generic classes with a fixed set of static constant instances. These classes appear to the user like Dart enumerated types would. For example, generic enums can be used in switch statements, to initialize variables, or as default parameters in functions and constructors.

The annotations defined in this library are:

  • @GenerateValueMap(): Requests the generation of an unmodifiable map _$<ClassName>ValueMap containing the enum values and const static instances.
  • @GenerateFromJson(): Requests the generation of the private function _$<ClassName>FromJson and the generation of _$<ClassName>ValueMap. Note: A ToJson function is already provided by the base class generic_enum.
  • @GenerateIdentifier(): Requests the generation of the private function _$<ClassName>Identifier. The function can be use to retrieve the identifier of each defined const generic enum instance.

Usage #

To use this library include generic_enum and generic_enum_annotation as dependency in your pubspec.yaml file. Include generic_enum_builder, source_gen, build_runner as dev_dependencies.

To create a generic enum class, say DpiResolution, the following steps are required:

  1. Extend GenericEnum<T>. To use the serialization methods, T should have fromJson and toJson methods.
  2. Define a private const constructor that calls the super constructor and passes on the value of type T.
  3. Define the static const instances of DpiResolution. You may capitalize instance names to mark them as constants.

The following steps are optional. They are only required if one needs access to a list of all defined values and instances or if json-serialization is needed. In principle, a map containing values and instances and serialization functions could be maintained manually. When defining several generic enumeration classes it might be more convenient to use a builder.

  1. Annotate the class with @GenerateFromJson.

  2. Define an accessor for the private variable _$DpiResolutionValueMap.

  3. Define a factory constructor named fromJson calling the private function _$DpiResolutionFromJson.

    import 'package:generic_enum/generic_enum.dart';
    import 'package:generic_enum_annotation/generic_enum_annotation.dart';
    
    //   0. Add a part statement pointing to the generated file.
    part 'dpi_resolution.g.dart';
    
    //   1. Extend GenericEnum<T>
    @GenerateFromJson()   //         <----------- 4. Annotate class
    class DpiResolution extends GenericEnum<int> {
      // 2. Define a private const constructor that calls the super constructor
      //    and passes on the value of type int.
      const DpiResolution._(int value) : super(value);
    
      // 3. Define static constant instances of type DpiResolution
      static const DpiResolution LOW = DpiResolution._(90);
      static const DpiResolution MEDIUM = DpiResolution._(300);
      static const DpiResolution HIGH = DpiResolution._(600);
    
      // 5. Give access to _valueMap and
      static Map<int, DpiResolution> get valueMap => _$DpiResolutionValueMap;
    
      // 6. Define the named factory constructor .fromJson:
      factory DpiResolution.fromJson(Map<String,dynamic> json) => _$DpiResolutionFromJson(json);
    
    }
    
  4. Configure the build targets (and amend the generate_for entry). In your local build.yaml file add the following targets:

    targets:
      $default:
        builders:
          # Configure the builder `pkg_name|builder_name`
          generic_enum_builder|map_builder:
            # Only run this builder on the specified input.
            enabled: true
            generate_for:
              - lib/*.dart
          # Configure the builder `pkg_name|builder_name`
          generic_enum_builder|json_builder:
            # Only run this builder on the specified input.
            enabled: true
            generate_for:
              - lib/*.dart
    
  5. Build the project by running the command

    $ pub run build_runner build --delete-conflicting-outputs
    

Examples #

The package generic_enum_example provides a complete example on how to define and build generic enumeration classes. As a starting point users could clone this repository, add their own generic enum classes to the folder lib and build the library.

Features and bugs #

Please file feature requests and bugs at the issue tracker.

0.0.1 #

Initial Version of the library.

0.0.2 #

Amended documentation.

0.0.3 #

Added folder tool.

0.0.4 #

Amended README.md.

0.0.5 #

Amended description in pubspec.yaml.

0.0.6 #

Added relative hyperlinks to README.md.

0.0.7 #

Added Travis badge.

0.1.0 #

Renamed @GenerateToFromJson to @GenerateFromJson.

0.1.1 #

Amended README.md. Added fct. prefix for gen. fcts.

0.1.2 #

Renamed annotation GenerateBuiltMap -> GenerateValueMap.

0.1.3 #

Amended docs.

0.1.4 #

Added annotation GenerateIdentifier.

0.1.5 #

Amended README.md.

example/README.md

Generic Enum Annotation #

Introduction #

This library defines annotation classes (with const constructor). These are used to annotate classes that extend GenericEnum.

GenericEnum is a base class for creating generic classes with a fixed set of static constant instances. These classes appear to the user like a Dart enum would. For example, generic enums can be used in switch statements, to initialize variables, or as default parameters in functions and constructors.

The annotations defined in this library are:

  • @GenerateValueMap(): Requests the generation of an unmodifiable map _$<ClassName>ValueMap containing the enum values and const static instances.
  • @GenerateFromJson(): Requests the generation of the private function _$<ClassName>FromJson.
  • @GenerateIdentifier(): Requests the generation of the private function _$<ClassName>Identifier. The function can be use to retrieve the identifier of each defined const generic enum instance.

Important: @GenerateFromJson() requires @GenerateValueMap() since the function _$<ClassName>FromJson uses the unmodifiable map _$<ClassName>ValueMap to retrieve generic enum instances based on their value.

Examples #

The package generic_enum_example provides a complete example on how to define and build generic enumeration classes. As a starting point users could clone this repository, add their own generic enum classes to the folder lib and build the library.

Features and #

Please file feature requests and bugs at the issue tracker.

Use this package as a library

1. Depend on it

Add this to your package's pubspec.yaml file:


dependencies:
  generic_enum_annotation: ^0.1.5

2. Install it

You can install packages from the command line:

with pub:


$ pub get

with Flutter:


$ flutter pub get

Alternatively, your editor might support pub get or flutter pub get. Check the docs for your editor to learn more.

3. Import it

Now in your Dart code, you can use:


import 'package:generic_enum_annotation/generic_enum_annotation.dart';
  
Popularity:
Describes how popular the package is relative to other packages. [more]
40
Health:
Code health derived from static analysis. [more]
100
Maintenance:
Reflects how tidy and up-to-date the package is. [more]
100
Overall:
Weighted score of the above. [more]
70
Learn more about scoring.

We analyzed this package on Feb 15, 2020, and provided a score, details, and suggestions below. Analysis was completed with status completed using:

  • Dart: 2.7.1
  • pana: 0.13.5

Dependencies

Package Constraint Resolved Available
Direct dependencies
Dart SDK >=2.6.0 <3.0.0