README.md: be more specific withDefaults application order

[spinus]

Contribution checklist (recommended but not always applicable/required):

• There's an automated test for this change
• Commit messages or code include references to related issues or PRs (including third parties)
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[spinus]

In relation to #1519

[Nebucatnetzer]

In general it looks good, some minor things and a few typos.

[Nebucatnetzer]

"it applies user overrides first and then applies defaults"

[Nebucatnetzer]

Please remember that the withDefaults function

Missing the

and then

Then instead of than.

If you want to change a package

Missing a.

[Nebucatnetzer]

Can you rewrite it like this?
The text and the code are separated by an empty line.

you can use the a snippet like the following which then puts your changes on top of the defaults:

```nix

[Nebucatnetzer]

@elikoga Can you explain to me the difference between the code snippet in this merge request and the way it is done here? jwpconsulting/projectify@5aef755

[elikoga]

@elikoga Can you explain to me the difference between the code snippet in this merge request and the way it is done here? jwpconsulting/projectify@5aef755

I believe it's just like justuswilhelm said in #1519 :

My overrides are created with

    overrides = defaultPoetryOverrides.extend (self: super: {

based off the poetry2nix flake guide, and just like @sigprof here recommended as well -- so perhaps that made a difference?

where extend is defined by https://noogle.dev/f/lib/makeExtensible

Compared to overrides.withDefaults, which is simply defined in poetry2nix and whose behaviour was changed in f36ad45

[sigprof]

The real problem is that some overrides work only when applied before defaultPoetryOverrides, but some other overrides work only when applied after defaultPoetryOverrides. So in the end I needed to resort to code like this:

    overrides = [
      # Some overrides (e.g., the ones which set preferWheel) must be applied
      # before the default overrides:
      # https://github.com/nix-community/poetry2nix/pull/899
      (self: super: {
        attrs = super.attrs.override {
          # attrs >= 24.3.0 requires hatchling >= 1.26.0 to build from source:
          #   https://github.com/python-attrs/attrs/pull/1377
          #   https://github.com/pypa/hatch/issues/1715
          preferWheel = true;
        };
      })

      poetry2nix.defaultPoetryOverrides

      # Apply most overrides after the default overrides, so that things like
      # overriding cargoDeps work even when the default overrides also do that:
      # https://github.com/nix-community/poetry2nix/issues/1519
      (self: super: {
        rpds-py = let
          getCargoHash = version: {
            "0.22.3" = "sha256-m01OB4CqDowlTAiDQx6tJ7SeP3t+EtS9UZ7Jad6Ccvc=";
          }.${version} or (
            lib.warn "Unknown rpds-py version: '${version}'. Please update getCargoHash." lib.fakeHash
          );
        in
          super.rpds-py.overridePythonAttrs(old: {
            cargoDeps = pkgs.rustPlatform.fetchCargoTarball {
              inherit (old) src;
              name = "${old.pname}-${old.version}";
              hash = getCargoHash old.version;
            };
          });
        });
      })
    ];

[elikoga]

From #899

why then have overrides.withDefaults if it can't be used sanely?

Since we already have poetry2nix.defaultPoetryOverrides why not deprecate the old function with a warning, then later removal or similar (in 2 nixos release cycles?)

If the api of the function can be changed to break for some users anyways, why not for all users?