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Learn Red ? Fundamentals of Red
book

Learn Red ? Fundamentals of Red

by Ivo Balbaert
May 2018
Beginner content levelBeginner
252 pages
6h 19m
English
Packt Publishing
Content preview from Learn Red ? Fundamentals of Red

Changing data – change, remove, and insert

Suppose we want to change the <title> tag in the rate string to <rate>. This is also something you can do with parse, using the change word:

parse rate [to "<title>" change "<title>" "<rate>"]      ;== falserate      ;== "<rate>1 USD = 0.81191502 EUR</title>"

Although parse didn't go through to the end (it returned false), the rate string has been changed!

Just to show how you can make a parse program more flexible by defining new words, we rewrite the same example:

start-tag: "<title>"change-tag: "<rate>"find-tag: [to start-tag]replace-tag: [change start-tag change-tag]parse rate [find-tag replace-tag]do-action: [find-tag replace-tag]parse rate do-actionrate ;== "<rate>1 USD = 0.81191502 EUR</title>" ...
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Publisher Resources

ISBN: 9781789130706Supplemental Content