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Ask HN: How do you familiarize yourself with a new codebase?

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Re: Ask HN: How do you familiarize yourself with a new codebase?

#81

Post by chillingeffect »

lukaslalinsky wrote: post #47
Mithaldu wrote: post #6

This may or may not apply to you, since i work with Perl. Typically i'm in a situation where i'm supposed to improve on code written by developers with less time under their belt. As such my first steps are: 1. tidy/beautify all the code in accordance with a common standard 2. read though all of it, while making the code more clear (split up if/elsif/else christmas trees, make functions smaller, replace for loops wit…

Please don't take this as a criticism, but how long have you been programming? I'm asking because I used to have an opinion like this when I was just starting, but after a few years I realized that changing all of the code as the first thing is one of the worst things to do.

>> i work with Perl >> user: Mithaldu >> created: 2099 days ago

> how long have you been programming?

Re: Ask HN: How do you familiarize yourself with a new codebase?

#83

Post by geertj »

My typical workflow for checking out new open source projects:

- find . -type f

- find . -name \* .ext | wc -l (get an idea of complexity)

- git log (is this thing maintained?)

- find . -name \* .ext | ctags

- find main entry points, depending on platform and language

- vim with NerdTree enabled

- CTRL-], CTRL-T to jump to browse tags in vim

Generally a lot of find, grep and vim gets me started.

Re: Ask HN: How do you familiarize yourself with a new codebase?

#84

Post by corysama »

I pick a function or an outcome and type out the pseudocode stack traces leading to that in notepad.

I include function names and the names of the variables passed as parameters. But, no braces or other syntax. Almost always omit branches/variable decls/error checking. Include all interesting function calls along the path, but omit any branches/function bodies that lead off the desired path. Inline callbacks as function calls with addition notation. If the process has separate steps that aren't a single call/callback tree, start a new tree with the note "then later..."

To do this, I have to start from the line of code that enacts the outcome and determine the backtrace with a combo of debugger stack traces and examining the code for branches/callbacks of interest.

But, when it's complete, I'll have the start-to-finish process of some complicated task in the code --usually on a single screen of text. It's a tremendously better use of my short term memory to scan over that than to constantly bounce around the actual code base.

Re: Ask HN: How do you familiarize yourself with a new codebase?

#85

Post by agentgt »

There is a significant number of answers that may interest you on Stackoverflow. Specifically: http://stackoverflow.com/questions/215076/whats-the-best-way...

Two things I do to familiarize with a code base is to look at how the data is stored. Particularly if its using a database with well named tables I can get some rough ideas of how the system works. Then from there I look at other data objects. Data is easier to understand than behavior.

The other is watching the initialization process of the application with a debugger or logger. Along those lines if your lucky (my opinion) and the application uses dependency injection of some sort you can look to see how the components are wired together. Generally there is an underlying framework to how code pieces work together and that generally reveals itself in the initialization process if its not self evident.

Re: Ask HN: How do you familiarize yourself with a new codebase?

#87

Post by jeremiep »

Mithaldu wrote: post #6

This may or may not apply to you, since i work with Perl. Typically i'm in a situation where i'm supposed to improve on code written by developers with less time under their belt. As such my first steps are: 1. tidy/beautify all the code in accordance with a common standard 2. read though all of it, while making the code more clear (split up if/elsif/else christmas trees, make functions smaller, replace for loops wit…

Both points aren't possible to do with large codebases.

It will take months merely to tidy the code with the effect of making the rest of the team hate you for committing thousands of files for superficial changes. Its much more productive for everyone to simply adapt to the existing style guidelines.

Reading all of the code is only an option for the smallest of codebases. Reading code will only get you so far before you get lost in the complexity of how all the parts interact with each other.

A better approach would be to limit yourself to a subset of the codebase and start poking around with a debugger while the system is running. Then you can gradually work your way through the codebase starting from the core functionality.

Re: Ask HN: How do you familiarize yourself with a new codebase?

#88

Post by vitorbaptistaa »

Mithaldu wrote: post #6

This may or may not apply to you, since i work with Perl. Typically i'm in a situation where i'm supposed to improve on code written by developers with less time under their belt. As such my first steps are: 1. tidy/beautify all the code in accordance with a common standard 2. read though all of it, while making the code more clear (split up if/elsif/else christmas trees, make functions smaller, replace for loops wit…

Do you follow this process even on code without tests? How do you make sure you're not introducing bugs in the process? Or you don't commit your changes afterwards?

Re: Ask HN: How do you familiarize yourself with a new codebase?

#89

Post by gshx »

I start with running the tests if there are any. Typically peeling layers of the onion starting with the boundary. If there are no tests, then I'll try to write them. Then running tests in debug mode helps step through the code. If I have the luxury of asking questions to an engineer experienced with the codebase, I request a high level whiteboarding session all the while being cognizant of their time.

Some others have mentioned recency/touchTime as another signal. For large complex codebases, that may or may not always work.

Re: Ask HN: How do you familiarize yourself with a new codebase?

#90

Post by bliti »

This codebase is documented and well structured. I would simply being by tackling the issues on github first and sending pull requests. No need to take over it right away. After you feel comfortable reading the code and knowing where is what, you can ask to become a maintainer.

I'd try to fix it using the same style used in the codebase. This way anybody else reading, maintaining ,or using it won't have to make sense of the new style. Pay attention to how each method is defined. They are very readable. Very few traces of complex one line statements.

Most importantly, be patient. You won't be any good with it in less than 2 weeks of constant tinkering. Good luck.

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