The Project Structure

In this guide I assume you know basic things such as how to use git to download the source code, programming concepts such as objects and services, and elemental C++ syntax. If not, click these links. They are going to be helpful.

Opening project for the first time

When you open MuseScore, Audacity or Advanced Effects you will see a project structure like the following:

- .github
- .tx
- buildscripts
- demos
- docs
- fonts
- hooks
- sandbox
- share
- src
- test
- thirdparty
- tools
- vtest
- .clangd
- LICENSE.txt
- CMakeLists.txt

And this might confuse beginners and first and make it seem much more complicated than it really is. But 99% of the time you only really need to care about two of these files: src/ and CMakeLists.txt.

This is one of the most important skills in programming and one that doesn't get taught in tutorials. See, 75% of the programming process isn't actually writing code. It's planning what you are going to write and how. The tutorials you see have already gone through that exploration phase and they only teach you about things like specific language syntax. But let's continue.

If you expand src/, you will then again see a large quantity of folders:

- app
- appshell
- appshell_web
- braille
- commonscene
- context
- converter
- engraving
- framework
- importexport
- inspector
- instrumentsscene
- musesounds
- notation
- palette
- playback
- print
- project
- stubs
- webbridge
- CMakeLists.txt

But then again, 99% of these folders are not necessary to understand the code and open a window.

Browsing and understanding what the code means requires some time, that is completely normal in a new project. But let's ask some questions: 'What is app/? Why should it be called that way?' and make some observations that could explain it.

• Ask questions: 'What does this folder do? What do you think it could do?' (Ex. appshell could be the application's GUI because the shell is the UI face of chromium, for example.)
• Make observations: What files does the folder have? (Ex. check if appshell/ has in fact UI files)
• Extract a conclusion: appshell/ is (or is not) the application's UI layer.

We don't know what app, framework or context mean. But we can discard options. We are looking for the start of the application (main.cpp) to get a feeling of how the source code works together.

We could start by discarting some options. I guess converter, importexport, project, stubs, ... are not essential to understanding the code for now, so for now we're discarding all of them. What we are left with is this:

- app
- appshell
- framework
- context
- CMakeLists.txt