I think this way makes more sense. Comments appreciated :-)

👍 from me.

This still needs some packaging, like in a config_changed object. I'll add that.

Well, there are two things we could do:
a) ask that only correct things are put into compiler.config_dependencies;
b) change compiler.config_dependencies into a set and ask for strings to be put into it, then post.uptodate() has to create a sorted list out of it and put it into a tools.config_changed object.

Which one do you prefer?

Let's keep the complexity in one place, otherwise for each compiler we have to know all this stuff about why it has to be a set and why it has to have a unique ID, and how unique it has to be, etc.

I'd say the compiler just has a list of strings, then the post creates a config_changed up to its own requirements out of it.

I think this is better because while there is a chance 3rd parties will want to write a compiler plugin, noone outside the project is touching Post.

Sounds good to me. And if anyone needs to add something more complex than simply a string (or several of them), or if the data depends on the post as well, they can still use the more complicated mechanism.

Without this, nikola is broken badly. Merging.

It is indeed. But there was something missing for pandoc and markdown: the compilers also inserted a list of strings into the list (instead of strings). Merging that, too.