Meta programming in .spec using Lua, is it heresy?

[voxik]

I am playing with ideas such as #2959 or #2892 and here is a proposal how to achieve that (and much more). This could be the .spec file:

%define subpackage() %{lua:
subpackage = arg[1]

subpackage_name = subpackage:match("\\n%%package%s*([^\\n]*)")

if subpackages == nil then
  subpackages = {}
end

subpackages[subpackage_name] = subpackage

if licenses == nil then
  licenses = {}
end

licenses[subpackage_name] = subpackage:match("\\nLicense:%s*([^\\n]*)")
}

%define subpackages() %{lua:
for k in pairs(subpackages) do
  print(rpm.expand(subpackages[k]))
end
}

%define licenses() %{lua:
local license = arg[1]

for k in pairs(licenses) do
  l = licenses[k]

  if l then
    if license then
      license = license .. " AND " .. l
    else
      license = l
    end
  end
end

print(license or "")
}

%{subpackage:
%package foo
Summary: foo subpackage
License: BSD

%description foo
This random subpackage

%files foo
}


Summary: Demonstration package for mining licenses from subpackages
Name: license-subpackages
Version: 1
Release: 1%{?dist}
License: %{licenses:MIT}

%description
Using Lua and "metaprograming", it is possible to do magic with .spec files
such as collecting licenses from subpackages.

%{subpackages}

%changelog
* Wed Mar 13 2024 Vít Ondruch <[email protected]>
- Initial version

The SRPM would look like this:

$ rpm -qp --qf "%{SPEC}" license-subpackages-1-1.fc41.src.rpm









Summary: Demonstration package for mining licenses from subpackages
Name: license-subpackages
Version: 1
Release: 1.fc41
License: MIT AND BSD

%description
Using Lua and "metaprograming", it is possible to do magic with .spec files
such as collecting licenses from subpackages.


%package foo
Summary: foo subpackage
License: BSD

%description foo
This random subpackage

%files foo


%changelog
* Wed Mar 13 2024 Vít Ondruch <[email protected]>
- Initial version

I can imagine quite a lot more done with something similar. This trick could be used to enable/disable subpackages at will. If there were requires/provides, they could be adjusted for systems such as SCL. Is there some functionality or tag which RPM does not support (yet?), no problem to implement it in such macro.

Is this going too far?

[voxik]

This would actually address #1225