How do you effectively learn programming by studying from a pre-existing codebase/project?

Posted by Sure-Peaks@reddit | learnprogramming | View on Reddit | 3 comments

So I am training to learn mobile app development, and was instructed to learn through checking past projects developed by the company (tho I still feel like I haven't even completed the basics yet...)

The problem was that earlier, I felt like I was given vague instructions on reading through the code and trying to understand how it worked from there; didn't help that I couldn't get the 2nd project I was given to run at all (combination of being outdated + needing a specific "flavor" to run that I really didn't get), so I was just trying to understand how everything worked by reading each individual line. Certainly I tried to make diagrams + guesswork here and there, but honestly the whole experience felt brain-melting and kinda blanked out by the end. Now uhh it's been like a few months wasted from this now

I looked up from other sources, and it seems learning from codebases is considered effective. But I feel like I'd perform better if I was given a step-to-step process like a workbook with sequential questions, rather than having to go in blindly with complete freedom. What would be the expected complete dum-dum idiot's process for learning from a codebase, instead of trying to read every line?

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FlatProtrusion@reddit

I hate that replies to such post will now quote some ai wrapper website that are advertisement disguised as advice now.

My advice is to find out what problem a specific service, or api is solving or doing. Find out its design pattern (if its even implementing one) and that should improve your understanding of it.

Different_Pain5781@reddit

it’s okay, we all start like this

skysparko@reddit

Don’t try to read everything line by line, that’s the fastest way to burn out.

A simpler way to approach it:

Start from the entry point Find where the app starts and trace the main flow at a high level.
Pick one feature Follow something specific like login or a screen flow end-to-end instead of the whole codebase.
Run it and experiment Change small things and see what breaks. That teaches way more than just reading.
Build a rough mental map Files, modules, how things connect. Don’t worry about full understanding yet.
Rebuild a small piece yourself Even a tiny feature. That’s where it actually clicks.

Also, if your basics aren’t solid yet, jumping into a big codebase will always feel overwhelming. It helps to practice on smaller, structured problems first and then come back. I had the same issue and used platforms like skillron.com for that kind of step-by-step practice before diving into larger codebases.