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Perl 6 Deep Dive

You're reading from  Perl 6 Deep Dive

Product type Book
Published in Sep 2017
Publisher Packt
ISBN-13 9781787282049
Pages 402 pages
Edition 1st Edition
Languages
Author (1):
Andrew Shitov Andrew Shitov
Profile icon Andrew Shitov

Table of Contents (15) Chapters

1. What is Perl 6? 2. Writing Code 3. Working with Variables and Built-in Data Types 4. Working with Operators 5. Control Flow 6. Subroutines 7. Modules 8. Object-Oriented Programming 9. Input and Output 10. Working with Exceptions 11. Regexes 12. Grammars 13. Concurrent Programming 14. Functional Programming 15. Reactive Programming

Using the actions class

The more complex a grammar becomes, the more complex the actions. Almost every rule or token in our current grammar has an action. Even if most of the actions are just one or two lines of code, the fact that the Perl 6 code is mixed with the grammar language makes reading the code difficult. Formatting the code also becomes a difficult task, as you need to add more spaces to indent the code properly. In this section, we will see what Perl 6 offers to tackle this issue.

All actions may be moved to a separate class. Thus, the complete grammar contains a grammar itself and an actions class. Correspondence between the grammar rules and tokens and the actions is achieved by simply giving the same names to the methods of the action class. Let us convert our grammar to use the split approach.

First of all, create a class for actions and pass it to the parser:

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