▼ |  | 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 | Backwards Compatibility
| Index

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### 5`` Expanding the User’s Program Text and Breaking

Macro-expanding a program may involve arbitrary computation and requires the setup of the correct language. To aid this, DrRacket’s tool interface provides drracket:eval:expand-program to help. Use this method to extract the fully expanded program text in a particular language.

Because expanding the user’s program may require DrRacket to evaluate arbitrary code that the user wrote, tools that expand the user’s program should also allow the user to break the expansion. To help with this, the tools interfaces provides these methods: enable-evaluation and disable-evaluation. Since your tool will be expanding the program text, you should be both overriding enable-evaluation and disable-evaluation to disable your tool and calling them to ensure that only one expansion is happening at a time.

Finally, DrRacket provides the set-breakables method. This method controls what behavior the Break button has.

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