▼ |  | Dr Racket Plugins

1 | Implementing Dr Racket Plugins
2 | Adding Languages to Dr Racket
3 | Creating New Kinds of Dr Racket Frames
4 | Extending the Existing Dr Racket Classes
5 | Expanding the User’s Program Text and Breaking
6 | Editor Modes
7 | Language-specific capabilities
8 | Check Syntax
9 | Teaching Languages
10 | drracket: get/ extend
11 | drracket: unit
12 | drracket: language
13 | drracket: language-configuration
14 | drracket: debug
15 | drracket: rep
16 | drracket: frame
17 | drracket: help-desk
18 | drracket: eval
19 | drracket: modes
20 | drracket: module-language-tools
21 | drracket: module-language
22 | Documentation Utilities
23 | Backwards compatibility
| Index

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### 4`` Extending the Existing DrRacket Classes

Each of the names:

- drracket:get/extend:extend-interactions-text

- drracket:get/extend:extend-definitions-text

- drracket:get/extend:extend-interactions-canvas

- drracket:get/extend:extend-definitions-canvas

- drracket:get/extend:extend-unit-frame

- drracket:get/extend:extend-tab

is bound to an extender function. In order to change the behavior of DrRacket, you can derive new classes from the standard classes for the frame, texts, canvases. Each extender accepts a function as input. The function it accepts must take a class as its argument and return a classes derived from that class as its result. For example:

> ( drracket:get/extend:extend-interactions-text
> ( lambda (super%)
> ( class super%
> ( define/public (method1 x) ... )
> ( super-new ))))

extends the interactions text class with a method named method1.
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