betterC examples?

[Mike Parker]

On Friday, 30 April 2021 at 22:22:05 UTC, sfp wrote:

>
> To be clear, I'm mostly interested in examples that show how to 
> structure a project. I'd like to know what the best way to 
> start using D in my current project is, how to call D from C, 
> and how to call C from D.
>

There is nothing special about the structure of a BetterC 
_project_. It's just a D project without the full feature set, so 
you can structure it in whatever way makes sense to you in terms 
of packages and modules.

As for the code, your main function should be `extern(C)`. 
Functions you want to make available to the C side should also be 
`extern(C)`, and will need equivalent declarations in C. DMD has 
an experimental feature to generate C headers for you via the 
`-HC` (`dmd -HC=?` for options). Then all that's left is to link 
the C objects into D or the D objects into C.

Beyond that, it's just a matter of making use of a limited subset 
of D features:

https://dlang.org/spec/betterc.html

I'm unaware of any specific open source projects that do what 
you're looking to (integrate new D code into an existing C 
project) especially any using CMake. But I would approach by 
isolating the new D code as a library. Then you can structure it 
however you like and just add the library to your C project's 
dependencies.

Alternatively, you could add individual D modules to your source 
tree and configure CMake such that they are compiled with a D 
compiler and a header generated for each.

I mean, there's no one way to go about this. But whatever you end 
up doing, please consider writing it up in a blog post for the D 
blog (email me at aldacron at gmail.com when you're ready) 
describing how you approached it, then your project could be an 
example for someone else.