`History` primitive?

[jaimergp]

Checklist

• I added a descriptive title
• I searched open requests and couldn't find a duplicate

What is the idea?

Add readers and writers to rattler so users can process conda-meta/history files.

Why is this needed?

Essential in imperative APIs like conda's. We need to know which specs the user has requested in the past because there's no declarative input file.

What should happen?

A reader should be able to parse a conda-meta/history file and provide access to the different revisions, and the accumulated specs. The writer should be able to write revisions and the associated specs per revision.

Additional Context

See conda's History class.

[kajal-jotwani]

can I work on this issue?

[wolfv]

I think it would be fine to have such a parser in rattler - although we will not adopt this format in our tools (rattler-build or Pixi) because in my opinion it's a very bad serialization format :)

[iamthebot]

@wolfv does that mean you're against allowing rattler to write history files (in addition to reading)? I get not actually using it (and agreed, history files are not great for this purpose. We use sqlite instead haha), but being able to write these files is essential for compatibility of environments with vanilla conda CLI.

[baszalmstra]

Ratller does already write a history file I believe! It just doesnt really update the history file, it just overwrites it on every installation.

[baszalmstra]

Oh and I think its just empty 😅

[iamthebot]

Yeah, even rewriting the history file would be fine. The status quo is the file exists but is empty.