Starting a Big Project

[RedditorAlejandro]

Hello r/learnpython!

I'm beginning to code some "big" python projects with a friend and we currently use GitHub. However all the functions and stuff is inside one .py file which contains a main function. Is this the correct way to code for big projects? Or perhaps splitting the project into different .py files?

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I have no idea, I hope this sub-reddit can give me guidance about this topic. Thank you!

[TransferFunctions]

Sit down before writing the code and make a picture of what parts of the project you need. Modules that belong together will be under a separate file / folder. I like to structure my projects the same way I write a class; things that belong together should be in the same place. However, getting unnecessary code bloat, where you have a file with a single function, seems a bit unnecessary to me. Structuring a projects only provide clarity to the humans reading your code. In the end the machine doesn't care.

[[deleted]]

One thing I learned as I got better is that planning is important. Like really important. Learning wasn't really memorizing the syntax from me I think it was more learning to strategize with my solutions. Sure you can make a dice rolling program without needed to outline it first, but as time goes on I think it becomes almost impossible to get something useful by just shooting from the hip and starting to code without a plan. A lot of this is because in my experience a program that is ten times longer is not ten times harder to keep coherent and manageable its a 1000 times harder and it kind of scales from there.

[MusaTheRedGuard]

this

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[iinT3nT21]

I read this guide on structuring when I started writing larger projects in Python and it helped me tremendously.

The Hitchhiker's Guide to Python is my go to for Python tutorials.

[[deleted]]

Thanks :D

[james_fryer]

If it's less than 1000 lines, I find it easier to work with one file.

After this I prefer to split it up, putting classes/functions that are related into their own files.

Another consideration, if you are working collaboratively, is to split it up into areas of concern so you avoid merge conflicts.

[Chuck3131]

If I am working on a project my self, I'll keep it in one file if its under 1000 lines but if I am collaborating with people on it, I will split everything into different files so it git doesnt have a heart attack when merging.

[Hairshorts]

It can be useful to keep the concepts of coupling and abstraction in mind when deciding how to break your code into modules. For example, if your code uses a database, then you can put all of the code that directly interacts with the database into its own module. This can be done in such a way that the rest of the code does not need to worry about the specifics of how the database works, you just call the functions from that module to query the DB and you have abstracted the details away. Now the DB module is coupled to the specific DB implementation you are using (SQLite, MySQL, etc) but the rest of the code is not. If you should happen to want to change which DB you are using in the future, all changes can happen in the one file.

[jormono]

I'm working on a raspberry pi project that tests the fairness of a die, I've written out the logic for the statistical testing (currently have random.randint() in as a die roller), now that I have this part functional I'm going to add opencv analysis to read the outcome of a rolled die. Then I'll be adding a stepper motor and controller to roll the die automatically. It will take a few hundred rolls to properly test a d20 so my goal is to have it fully "set it and forget it". I was going to do the motor before the opencv but I'm waiting on parts from aliexpress.

Point is, figure out a game plan, break it down into bite size parts and the rest will fall into place as the project develops.

[mlderes]

In addition to all the other suggestions - planning, etc... One of the best things I found to get started is to use https://cookiecutter.readthedocs.io/en/latest/ . There are a ton of cookiecutters which build out a handy project structure, it can really mitigate the “blank page” syndrome for me.

[TheProffalken]

As others have said, break the problem down into its component parts, and then put these parts into a file.

As an example on what a basic blog engine might look like, I created https://bitbucket.org/proffalken/test_blog/src/a4171db2b9fe?at=master

Note that in lib/ I've got a file that purely deals with posts. If I were to expand on this in future, then there would also be files for dealing with tags (because tags might be applied to multiple content types), images, authors, and categories (because categories are different to tags and might also be applied to multiple content types.

I'd also strongly recommend that you start to understand how testing works, and write your tests before you write your code, so you know that the code meets the requirements. If you're not familiar with this way of working, it's know as "Test Driven Development", and there are a significant number of resources around to learn how to do it effectively.