Good file watching that provides flexible primitives absolutely requires:
- ok, a single ext4 file inode changes, and its filename matches my hardcoded string
- oh, you don’t want to match against just changes to “package.json” but you want to match against a regex? voila, now you need a regex engine
- what about handling a directory rename? should that trigger matches on all files in the renamed directory?
- should the file watcher be triggered once per file, or just every 5ms? turns out this depends on your use case
- how do symlinks fit into this story?
- let’s say i want to handle once every 5ms- how do i actually wait for 5ms? do i yield the thread? do i allow other async contexts to execute while i’m waiting? how do those contexts know when to execute and when to yield back to me? now you have an async runtime with timers
- how does buffering work? are there limits on how many file change events can be buffered? do i dynamically allocate more memory as more file changes get buffered? now you need a vector/arraylist implementation
And this is before you look at what this looks like on different platforms, or if you want polling fallbacks.
Can you do it with less dependencies? Probably, if you start making hard tradeoffs and adding even more complexity about what features you activate - but that only adds lines of code, it doesn’t remove them.
What you describe is ideologically nice, but in practice it’s over-optimizing for a goal that most people don’t really care about.