▼ |  | 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 | Signatures
11 | drracket: get/ extend
12 | drracket: unit
13 | drracket: language
14 | drracket: language-configuration
15 | drracket: debug
16 | drracket: rep
17 | drracket: frame
18 | drracket: help-desk
19 | drracket: eval
20 | drracket: modes
21 | drracket: module-language-tools
22 | drracket: module-language
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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