API tweaks

[dhardy]

Some details of the API are open to tweaking.

• Code tag: #0040

[dhardy]

• discover recursivity & following links

The discover module uses the walkdir crate to recursively files. This crate uses a builder pattern to allow restriction of the depth of the walk and control whether links are followed; it would be nice to expose these options — preferably via named default function arguments, but this feature is not (yet) available in Rust.

[dhardy]

• discover with partial paths

The discover functions could support partial paths. Example:

$ ls samples/repo-seq-small/
pn1-ss0-cl0.piplog  pn1-ss0.pip  pn1-ss1.pip
$ cargo run --example pippincmd -- -PSL samples/repo-seq-small/pn1-ss

[dhardy]

In the Partition type:

• the way user_fields are passed to write and write_snapshot may want to be different
• returning file headers from load and load_range (or via other methods) might be useful

[dhardy]

• Is there a way of auto-boxing structs passed to Partition::open, create (and repo equivalents)?

Yes, but I think it's probably not worth doing (partly because I don't wish to make these methods into templates).

[dhardy]

• UserFields & MakeMeta

Currently these get passed into nearly all methods which might use them, and some (e.g. Partition::create) now require two: user: Option<&mut UserFields>, make_meta: Option<&MakeMeta>. Partition::create(io, "replay part", None, None) is not so pretty.

[dhardy]

• Lists/maps of things within structs

Several struts store lists/sets/maps which should be user-readable: elements within a PartState, states, commits and "pending commits" within a Partition, changes within a Commit. Sometimes the underlying type can be accessed via a method which is convenient but fixes the type. Sometimes only a limited set of operations is possible.

[dhardy]

• Move want_snapshot out of PartIO?

Rationale: it's there to allow configuration of when snapshots are made, not how data is loaded/saved; additionally, the discover module provides a ready-to-use implementation of PartIO but it's not obvious how to do this while still allowing customisation of another method in the same trait.

[dhardy]

• Revise user-field funcs?

We have the following. Should snapshot and log file numbers be passed?

fn make_user_data(&mut self, _header: &FileHeader) -> Result<Vec<UserData>>;
fn read_header(&mut self, _header: &FileHeader) -> Result<()>;