6.5 Mixins

► |  | The Racket Reference

1 | Language Model
2 | Notation for Documentation
3 | Syntactic Forms
4 | Datatypes
5 | Structures
6 | Classes and Objects
7 | Units
8 | Contracts
9 | Pattern Matching
10 | Control Flow
11 | Concurrency and Parallelism
12 | Macros
13 | Input and Output
14 | Reflection and Security
15 | Operating System
16 | Memory Management
17 | Unsafe Operations
18 | Running Racket
| Bibliography
| Index

▼ | 6 | Classes and Objects

6.1 | Creating Interfaces
6.2 | Creating Classes
6.3 | Creating Objects
6.4 | Field and Method Access
6.5 | Mixins
6.6 | Traits
6.7 | Object and Class Contracts
6.8 | Object Equality and Hashing
6.9 | Object Serialization
6.10 | Object Printing
6.11 | Object, Class, and Interface Utilities
6.12 | Surrogates

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mixin

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#### 6.5`` Mixins🔗ℹ

> > syntax
> > (mixin (interface-expr ...) (interface-expr ...)
> > class-clause ...)

Produces a mixin, which is a procedure that encapsulates a class extension, leaving the superclass unspecified. Each time that a mixin is applied to a specific superclass, it produces a new derived class using the encapsulated extension.

The given class must implement interfaces produced by the first set of interface-exprs. The result of the procedure is a subclass of the given class that implements the interfaces produced by the second set of interface-exprs. The class-clauses are as for class*, to define the class extension encapsulated by the mixin.

Evaluation of a mixin form checks that the class-clauses are consistent with both sets of interface-exprs.

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