5 Expanding the User's Program Text and Breaking

▼ |  | Plugins: Extending Dr Racket

1 | Implementing Dr Racket Tools
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 | drracket: get/ extend
10 | drracket: unit
11 | drracket: language
12 | drracket: language-configuration
13 | drracket: debug
14 | drracket: rep
15 | drracket: frame
16 | drracket: help-desk
17 | drracket: eval
18 | drracket: modes
19 | drracket: module-language-tools
20 | drracket: module-language
21 | 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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