Master programming syntax, solve interactive challenges & run live code in Syntaxis Explore Arena →
menu_book Course Curriculum (Dart) expand_more
Foundations
Main function Var and explicit types Final and const Built-in numeric types String interpolation Records Null safety Late variables
Control Flow
If statements Switch expressions Switch patterns For loops For in loops While loops Break and continue Assert statements
Functions
Optional positional parameters Named parameters Required named parameters Arrow functions Closures Function typedefs Tear-offs Generator sync star
Collections
List Set Map Collection if Collection for Spread operator Null-aware spread Iterable transformations
Classes
Constructors Named constructors Factory constructors Const constructors Getters and setters Static members Abstract classes Interfaces
Inheritance and Mixins
Extends Implements With mixins Mixin class Sealed class Base class Final class Extension methods
Generics and Types
Generic classes Generic methods Bounded type parameters Covariant keyword Is type test As cast Patterns destructuring Extension types
Errors and Async
Throw Try catch Finally Custom exceptions Future Async await Stream Await for
Isolates and I/O
Isolate.run SendPort and ReceivePort File readAsString File writeAsString Directory listing URI parsing HTTP client JSON encode decode
Packages and Testing
Pubspec dependencies Package imports Library parts Metadata annotations Test package Mocking boundaries Lints Dart format
Dart / Packages and Testing

Library parts

Learn library parts in Dart through a focused explanation, a dedicated topic-specific example, an engineering boundary, and a mastery check.

12 min read • Advanced

library parts is an atomic Dart topic inside Packages and Testing. The example uses the named construct directly so you can see its syntax, data flow, and observable behavior.

Read the code by locating the exact feature named library parts, then trace the value before and after that feature runs. This lesson is intentionally isolated from neighboring topics: changing identifiers alone would not reproduce the same behavior because the construct itself is different.

Topic-specific example

dart-0075-2048f5c93b.dart
dart Try It Live 
library demo;
// part 'models.dart';
void main()=>print('library demo');
Edge case / engineering note

For library parts, test the boundary that makes the feature meaningful: invalid input, an empty value, a missing branch, lifecycle/cleanup, or a type/runtime constraint. Do not infer correctness only from the happy path.

Content source & attribution
Original Syntaxis Content · Original Syntaxis Content

Lesson quizzes

Library parts Mastery Check →
← PREVIOUS
Package imports
NEXT →
Metadata annotations