6.10 Object Printing

To customize the way that a class instance is printed by print, write and display, implement the printable<%> interface.

value
printable<%> : interface?

The printable<%> interface includes only the custom-print, custom-write, and custom-display methods. The custom-print method accepts two arguments: the destination port and the current quasiquote depth as an exact nonnegative integer. The custom-write and custom-display methods each accepts a single argument, which is the destination port to write or display the object.

Calls to the custom-print, custom-write, or custom-display methods are like calls to a procedure attached to a structure type through the prop:custom-write property. In particular, recursive printing can trigger an escape from the call.

See prop:custom-write for more information. The printable<%> interface is implemented with interface* and prop:custom-write.

value
writable<%> : interface?

Like printable<%>, but includes only the custom-write and custom-display methods. A print request is directed to custom-write.

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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

6.1	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