Defensive Programming (Nomad)

Defensive programming may sound like something your granddad did after the war, but it’s key to reducing the number of bugs and increasing maintainability. We’re going to look at what defensive programming is and some steps to doing it in PHP.

Transcript

1. Defensive Programming
2. Use a Framework
3. Don't Trust Users
4. Filter User Content
5. filter_var( $input, FILTER_VALIDATE_BOOLEAN, FILTER_NULL_ON_FAILURE );
6. filter_var( $input, FILTER_VALIDATE_BOOLEAN, FILTER_NULL_ON_FAILURE );
7. filter_var( $input, FILTER_VALIDATE_BOOLEAN, FILTER_NULL_ON_FAILURE );
8. → FILTER_VALIDATE_EMAIL → FILTER_VALIDATE_IP → FILTER_VALIDATE_REGEXP → FILTER_VALIDATE_URL
9. v::alnum() ->length(1,15) ->validate("PHP 6"); // true
10. → https://php.net/manual/en/function.filter-var.php → https://php.net/manual/en/filter.filters.validate.php → https://github.com/respect/validation
11. Use Database Abstractions
12. → http://www.doctrine-project.org/projects/orm.html → https://github.com/auraphp/Aura.Sql
13. Sanitise User Content
14. → http://php.net/manual/en/function.strip-tags.php → http://php.net/manual/en/function.htmlentities.php
15. Don't Trust Developers
16. Write Tests
17. → http://grumpy-learning.com
18. Follow SOLID Principles
19. Single Responsibility Principle
20. Open-Closed Principle
21. Liskov Substitution Principle
22. Interface Segregation Principle
23. Dependency Inversion Principle
24. → https://cleancoders.com
25. Type-hint
26. function average(array $values = []) { return array_sum($values) / count($values); }
27. function print_script($src) { assert( is_string($src), "src is not a string" ); print "<script src='{$src}'></script>"; }
28. Thanks! → https://joind.in/13401 → https://twitter.com/assertchris