`buildPython*`: Document arguments unable to reference directly from `finalAttrs`

[Sigmanificient]

• treewide: move python packages I maintain to finalAttrs #476981

While migrating my python packages to the new finalAttrs pattern, i encountering the following issue:

buildPythonPackage (finalAttrs: {
  pname = "aerosandbox";
  version = "4.2.8";
  format = "wheel";

  src = fetchPypi {
    pname = "AeroSandbox";
    inherit (finalAttrs) version format;

    python = "py3";
    dist = "py3";
    hash = "sha256-+rrZzaBWyc9a20bUlsB0iDqYkn+ldlKT0lFfCy2yeXk=";
  };

 # ...
})

fails to biuld:

       error: attribute 'format' missing
       at /home/sigmanificient/repos/nixpkgs/pkgs/development/python-modules/aerosandbox/default.nix:24:34:
           23|     pname = "AeroSandbox";
           24|     inherit (finalAttrs) version format;
             |                                  ^
           25|

This seems to be related to the attributes listed in excludeDrvArgNames, because i have a similar issue with shiny and optional-dependencies.

Edit:

This affects attributes such as format or optional-dpenendencies
I seems that it might be something different than excludeDrvArgNames

• https://github.com/NixOS/nixpkgs/pull/271387/changes#diff-c263b18f23de7c1f00ed846783c3b977718aae8cdfdd89fc82adcf365d1d8bebR107-R120

Are attributes listed as string in excludeDrvArgNames not accessible using finalAttrs.${attr-name}?

For theses attributes should i use:

• (finalAttrs: rec { ... })
• finalAttrs.finalPackages.${attr}
• wait for a fix?

@ShamrockLee

[ShamrockLee]

format should be referenced as finalAttrs.passthru.format; the same for pyproject. I made the design decision in PR #376372 to avoid mass rebuilds and to avoid dealing with the interactions between pyproject and format.

I'm not sure if it was a wise decision, as they don't have context and changing them almost certainly rebuilds the package.

(Some other attributes like build-system, dependencies and optional-dependencies are placed in passthru for a reason. )

[Sigmanificient]

Thanks for the quick reply! Are excludeDrvArgNames following this rule? I am absolutely unable to read the pr you pointed to, it is way above my understanding of nixpkgs 😅

[ShamrockLee]

@Sigmanificient In addition, do you think it is a good idea to inherit format from the main package in fetchPypi?

[Sigmanificient]

I think there are a few instances of this pattern, at least for format = "wheel"

[ShamrockLee]

Are excludeDrvArgNames following this rule

Could you elaborate?

I am absolutely unable to read the pr you pointed to, it is way above my understanding of nixpkgs 😅

The finalAttrs is provided by stdenv.mkDerivation. According to pkgs/stdenv/generic/make-derivation.nix, it could be thought of as "the final state of the arguments passing stdenv.mkDerivation" plus two extra attributes overrideAttrs and finalPackage.

excludeDrvArgNames is to avoid passing the named arguments to constructDrv automatically when specified by the user.

[ShamrockLee]

I think there are a few instances of this pattern, at least for format = "wheel"

@mweinelt What do you think?

[mweinelt]

Inheriting the format is a speciality we only see in the pypi fetcher to my knowledge.