value_t2_generator

Description:

value t2 generator

value_t2 #
Reasoning: #
specifying clases with copywith, equals, toString, required constructor fields and other standard features is actually a fair amount of work resulting in verbose code which makes it difficult to maintain and difficult to read.
typeclasses (ish), value types (ish)
Solution: use value_t2 #
Basic features #

Equality

var bob1 = Person(age: 5, name: "bob");
var bob2 = Person(age: 5, name: "bob");

bob1 == bob2; //true
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CopyWith (works on subclasses in same file)

var bob = Employee(age: 5, name: "bob", id: "123);
var bobby = bob.cwPerson(age: 6, name: "bobby");
var robert = bob.cwEmployee(age: 25, name: "robert", id: "123);

bobby is Employee; //true
robert is Employee; //true
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ToString

var bob = Person(age: 5, name: "bob");
bob.toString() //age:5|name:"bob"
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All fields are required, non nullable (through assert pattern) and final by default

var bob = Person(age: 5, name: "bob");
bob.age = 6; //error

//warning on missing parameter values
var bob = Person(age: 5);

//assert error if parameter is null
var bob = Person(age: 5, name: null);
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More examples #
For more examples look at the Examples project in the github repository
Installation #

Import value_t2_annotation, value_t2_generator, quiver_hashcode and build_runner

dependencies:
value_t2_annotation:
quiver_hashcode:

dev_dependencies:
build_runner:
value_t2_generator
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Usage #

Add three imports at top of each file

import 'package:meta/meta.dart';
import 'package:quiver_hashcode/hashcode.dart';
import 'package:value_t2_annotation/value_t2_annotation.dart';
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Place a @ValueT2() annotation on every class
Prepend a dollar on the classname or two dollars for abstract classes when defining a class
Declare all classes as abstract

abstract class $$MyAbstract class {

abstract class $MyClass class {
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when using the class don't use the dollar sign

MyClass(a: "value")
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simple definition

@ValueT2()
abstract class $Pet {
String get type;
}
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simple definition with implements

@ValueT2()
abstract class $Person {
String get name;
}

@ValueT2()
abstract class $Employe implements $Person {
String get id;
}
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never use extends, only interfaces

@ValueT2()
abstract class $B implements $A {
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More features #

Shorter and more simple syntax

@ValueT2()
abstract class $A {
String get aValue;
}

//vs

class A {
final String aValue;

A({
@required this.aValue,
}) : assert(aValue != null);

//toString, hasCode, ==
}
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The properties of interfaces are implemented automatically (no need to specify them, just use implements)

@ValueT2()
abstract class $A {
String get aValue;
}

@ValueT2()
abstract class $B implements $A {
String get bValue;
}

var b = B(aValue: "A", bValue: "B");
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Can override a property of a subclass

@ValueT2()
abstract class $A {
Person get a;
}

@ValueT2()
abstract class $B implements $A {
Employee get a;
}
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Can specify generics

@ValueT2()
abstract class $$A<T1, T2> {
T1 get x;
T2 get y;
}

@ValueT2()
abstract class $B implements $$A<int, String> {
String get z;
}
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Limitations #

Custom getters are not supported

use functions instead


Methods on a class are not supported (use functions instead)
'go to definition' takes you to the generated class

workaround1 - to get class info hover over the class
workaround2 - go to definition, then go to definition a second time to go to the dollar version of class
possible update in the future



Coming (if others want and are interested) #
See github issues