Option to report only changed files

[StarpTech]

As titled. The quiet options will print also untouched files.

[wooorm]

Closest to this is the --watch argument on the CLI (unified-args)

This is pretty interesting, but not doable easily. E.g., what is a “change”?

• Is that a change in the contents of a file?
• Or a different file path (file.path !== file.history[0])
• Should we start supporting stats, and track changes to mode, mtime, and the like?

I think this would be roughly related to GH-22 too.

[StarpTech]

Yes, it's a change in the original file when I use output: true

[StarpTech]

Why it should be related to a cache?

[wooorm]

It doesn’t have to be, but my above three points are also what’s needed for caching. Albeit that “changed” files, as described above, relate to comparing a file before processing to after processing, whereas caching compares them between processes.

[StarpTech]

OK I got but for clarification my issue is only about to list which files are touched. Touch means as soon as I change the original content of the file (option: output).

[wooorm]

Wait, are you talking about written files, instead of “changed” files?

[StarpTech]

No, I'm talking about updated files. List all written files is already supported but it doesn't help because it shows all found files based on the pattern.

[wooorm]

Well, that’s hard. And then we need a definition of changed, and my proposal in my first comment is that I believe?

[StarpTech]

Yes. My proposal: changed means when source content != content (after processing). It doesn't matter if the content is saved to a different location when the content was changed.

[wooorm]

First what we need to figure out is how to check if file.contents (string or buffer) equals a file on disk. I’m thinking node-stream-equal could work, if file.contents was made into a stream.
Any other thoughts?

Next steps would be to wrap that in a vfile-matches-file-on-disk utility (which obviously needs a better name). And then to filter the files here using that utility if a flag is set.