6 Expanding the User's Program Text and Breaking

▼ |  | Dr Racket Plugins

1 | Tool support for #lang-based Languages
2 | Implementing Dr Racket Plugins
3 | Adding Languages to Dr Racket
4 | Creating New Kinds of Dr Racket Frames
5 | Extending the Existing Dr Racket Classes
6 | Expanding the User’s Program Text and Breaking
7 | Editor Modes
8 | Plugin Capabilities
9 | Check Syntax
10 | Cooperating with Background Check Syntax
11 | Teaching Languages
12 | Signatures
13 | drracket: get/ extend
14 | drracket: unit
15 | drracket: language
16 | drracket: language-configuration
17 | drracket: debug
18 | drracket: rep
19 | drracket: frame
20 | drracket: help-desk
21 | drracket: eval
22 | drracket: modes
23 | drracket: module-language-tools
24 | drracket: module-language
25 | drracket: tracing
26 | drracket: init
27 | Backwards Compatibility
| Index

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## 6 Expanding the User’s Program Text and Breaking🔗ℹ

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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