type_plus 0.3.0

Give your types superpowers and spice up your generics. Make types great again.

Type Plus

Give your types superpowers and spice up your generics. Make types great again.

type_plus is a utility package to bring some advanced capabilities to type variables and generic type arguments With type_plus you can easily deconstruct any type variable or generic type argument.

import 'package:type_plus/type_plus.dart';

class Person {}

class Box<T> {}

abstract class Group extends Iterable<Person> {}

void main() {
  // first, specify all types using this syntax
  TypePlus.addFactory((f) => f<Person>());
  // or this simple version for non-generic types
  TypePlus.add<Person>();

  // for generic types, use a generic function
  TypePlus.addFactory(<T>(f) => f<Box<T>>());
  // for extending classes, make sure to put all supertypes
  TypePlus.add<Group>(superTypes: [typeOf<Iterable<Person>>()]);

  // get a type variable
  Type personType = Person;
  // for generic types, use this helper function
  Type boxOfString = typeOf<Box<String>>();

  print(personType.name); // the name of the type: Person
  print(personType.id); // the id of the type: (some unique number)

  print(boxOfString.base); // the base type: Box<dynamic>
  print(boxOfString.args); // the type arguments: [String]

  myFunction<Person>(); // prints "Hi!"
  myFunction<Box<int>>(); // prints "Box of ints"

  Function printType = <T>() => print(T);
  // invoke a generic function with the full type
  printType.callWith(typeArguments: [boxOfString]); // prints: "Box<String>"
  // invoke a generic function with the type arguments
  printType.callWith(typeArguments: boxOfString.args); // prints: "String"

  String boxId = boxOfString.base.id; // id of the base type
  String personId = personType.id;

  // construct a new type by it's id
  Type newType = TypePlus.fromId('$boxId<$personId>');
  print(newType); // prints: "Box<Person>"

  // check if a type implements another type
  print(newType.implements(Box)); // prints: "true"
  print((Group).implements(typeOf<Iterable<Person>>())); // prints: "true"
  // or the other way around
  print((num).implementedBy(int)); // prints: "true"
}

void myFunction<T>() {
  if (T.base == Person) {
    print("Hi!");
  } else if (T.base == Box) {
    print("Box of ${T.args.first}s");
  }
}