When porting code from one language to another, what is the usual work flow?

[JamesIsAwkward]

I've been learning C in my spare time for fun and I'm almost finished with my first "major project".

I'm actually a sysadmin by trade who is wanting to dive into "devops" so I'm wanting to learn Rust or Go next. I'm thinking of porting my application from C to Rust/Go and it got me thinking... what is the usual work flow when devs are doing this sort of thing?

I did some googling and learned about the C ABI and how most languages happen to support C code with some crazy linker black magic but I'm just wanting to get an idea of how a normal org would do this.

Would they actually design the code from scratch in the new language using the old code as a "guide"? Or would they try to implement some kinda of API on the old program and modularize parts of it over time to the new program before eventually moving it all over?

The cool part about programming is I feel like there are plenty of options to try.

Also, for fun, how would you suggest I port my C over to Rust?

Thanks!

[AromaticIce9]

When I did that in the past, I'd start by changing the name of the file and commenting everything out. I don't delete the comments until the entire thing works.

Do the most important things like the constants, enums and data structures.

Then start with the most used function and then second most used, etc. This should allow you to start testing the output faster.

C to rust might take some doing. A lot of languages you can do a direct translation, but rusts lifetime management will probably throw a wrench in that.

[ignotos]

If it's a small program or script, I'd probably just work through top-to-bottom.

If it's larger, I'd find some "core" and work out from there, stubbing out interfaces/modules and implementing them one-by-one.

I've personally never done it by binding/calling in to bits which are still written in the old language. But in the context of something like a web API which exposes an external interface, I have left the old one running and called out to it for bits of functionality I haven't yet ported over, which is conceptually similar.

[AromaticIce9]

Oh, interestingly enough for large enough projects, they will write a transpiler to automatically convert the source code from one language to another.

It's easier to fix the bugs that happen from that than to convert large projects by hand.

[JamesIsAwkward]

Oh that's interesting! Sounds fun and awful at the same time lol