Reading Code (Devoxx) - Speaker Deck

Reading Code (Devoxx)

by Marit van Dijk

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Reading Code Devoxx, Oct 10th 2024 https://maritvandijk.com/

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Reading Code • We spend more time reading code than writing code

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Reading Code We read code when: • adding features • fi xing bugs • understanding a new system • doing code reviews • learning new technologies • etc.

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Reading Code "developers on average spend as much as 58% of their time comprehending existing source code" - Felienne Hermans, The Programmer's Brain

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Reading Code • We spend more time reading code than writing code • But we don't practice reading code explicitly (much)

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Readability When we do talk about readability, it's often about writing readable code.

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Reading Code "How to teach programming (and other things)?" by Felienne Hermans https://www.youtube.com/watch?v=g1ib43q3uXQ

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Reading Code • What if we practice reading code explicitly?

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Code Reading Club • Code Reading Club https://codereading.club/

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The stars aligned Do you want to join our code reading club?

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Code Reading Club • Printed code sample • Structured exercises

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Examples of exercises • First glance • Identify components & relationships

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Examples of exercises • First glance • Identify components & relationships • Most important lines

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Examples of exercises • First glance • Identify components & relationships • Most important lines • Identify concepts

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Examples of exercises • First glance • Identify components & relationships • Most important lines • Identify concepts • Summary

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Code Reading Club Learned about ... • reading code

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Code Reading Club Learned about ... • reading code • other peoples' perspectives

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Code Reading Club Learned about ... • reading code • other peoples' perspectives • making my own assumptions explicit https://maritvandijk.com/code-reading-club/

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Reading Code

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Reasons why code is confusing 1. Lack of knowledge 2. Lack of information 3. Lack of processing power in the brain

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Cognitive processes • Long term memory • Short term memory • Working memory

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Lack of knowledge • Programming domain • Language / syntax • Programming constructs / algorithms • Business domain • Domain concepts • Business logic

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Dealing with a lack of knowledge • Create a list • Research • Memorise (if relevant)

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Lack of information • Unknown details • Unfamiliar names • Code connected in unknown ways • Too many things at once

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Dealing with lack of information • Chunking

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Dealing with lack of information • Chunking • Concepts & patterns

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Lack of processing power in the brain • Too many processing steps • Too many variables

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Dealing with lack of processing power in the brain • Memory aids • Dependency graph • State table

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Dependency graph

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State table public class NestedLoop { public static void main(String[] args) { for (int i = 0; i < 2; i++) { System.out.println("i is: " + i); for (int j = 0; j < 2; j++) { System.out.println("j is: " + j); } } } }

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Dimensions of code reading • Structure • Domain • Concepts • Context 💔

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Structure Code is not read linearly

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Domain • Behavior • Data

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Concepts

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Context

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Reading Code The bigger picture

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Understanding a new code base • Joining a new team / organisation • Using a new code base

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Reading Code • What does the code do?

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Context

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Reading Code A good place to start: • Check out the code

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Help in the IDE

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Help in the IDE • Project structure • Build & run • README • Dependencies • Diagrams

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Strategies • Identify components • Identify relationships / dependencies • Identify concepts • Gain context

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A slice of the application

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Find a starting point

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Find a starting point • Generic • Main method • Endpoint • Speci fi c • Error message / Exception • Logic / Functionality

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Help in the IDE

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Help in the IDE • Search • Navigate

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Strategies • A particular use case • Draw your own diagrams

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Reading Code Understanding a piece of code

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Reading Code • Structured exercises

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Help in the IDE

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Help in the IDE • Structure • Hints from your IDE • Tests • Debugging • Refactor for understanding • Context • AI Assistant

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No content

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Strategies • Structured exercises • Memory aids • Dependency graph • State table • Gain context

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Reading Code What's next?

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Structured exercises • Code Reading Club: https://codereading.club/ • Code Reading Club Resources: https://github.com/CodeReadingClubs/Resources • The Programmer's Brain - Felienne Hermans