Debugging

Transcript

1. Wojciech @sharnik haikuco.de

2. Programming is like riding a bike.

3. Except the bike is on fire and you're on fire

   and everything is on fire and you're actually in hell.
4. None

5. Main programming tasks: » Adding bugs » Removing bugs

6. Debugging

7. Know what you're trying to do

8. Inputs -> Program -> Outputs Calculator.add(2, 3) # => 5

9. Workflow

10. Reproduce the error

11. Make a hypothesis

12. Fix

13. Profit

14. If that didn't help, rollback

15. Techniques

16. Puts debugging class Calculator def add(a, b) puts a puts

    b a + b end end result = Calculator.new.add(2, 3) puts result

17. strings vs numbers ruby -e "x = 3; puts x"

    # => 3 ruby -e "x = '3'; puts x" # => 3 ruby -e "x = 3; puts x.inspect" # => 3 ruby -e "x = '3'; puts x.inspect" # => "3"

18. p: shorter puts X.inspect class Calculator def add(a, b) p

    a p b a + b end end result = Calculator.new.add(2, 3) p result

19. debugger: pry + byebug require 'pry-byebug' class Calculator def add(a,

    b) binding.pry a + b end end Calculator.new.add(2, 3)

20. Strategies

21. "Wolf fence" algorithm

22. Rubber duck debugging

23. Practice

24. Exercise gist.github.com/sharnik/2aedd681e6bcf81a7697 Remember » understand expectations » pinpoint where the

    bug is » find what the bug is » fix it