feat: overhauled template system (WIP)

templates/python/flake.nix

@@ -0,0 +1,134 @@
+{
+  description = "Hello world flake using uv2nix";
+
+  inputs = {
+    nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
+
+    pyproject-nix = {
+      url = "github:pyproject-nix/pyproject.nix";
+      inputs.nixpkgs.follows = "nixpkgs";
+    };
+
+    uv2nix = {
+      url = "github:pyproject-nix/uv2nix";
+      inputs.pyproject-nix.follows = "pyproject-nix";
+      inputs.nixpkgs.follows = "nixpkgs";
+    };
+
+    pyproject-build-systems = {
+      url = "github:pyproject-nix/build-system-pkgs";
+      inputs.pyproject-nix.follows = "pyproject-nix";
+      inputs.uv2nix.follows = "uv2nix";
+      inputs.nixpkgs.follows = "nixpkgs";
+    };
+  };
+
+  outputs =
+    { nixpkgs
+    , uv2nix
+    , pyproject-nix
+    , pyproject-build-systems
+    , ...
+    }:
+    let
+      inherit (nixpkgs) lib;
+
+      # Load a uv workspace from a workspace root.
+      # Uv2nix treats all uv projects as workspace projects.
+      workspace = uv2nix.lib.workspace.loadWorkspace { workspaceRoot = ./.; };
+
+      # Create package overlay from workspace.
+      overlay = workspace.mkPyprojectOverlay {
+        # Prefer prebuilt binary wheels as a package source.
+        # Sdists are less likely to "just work" because of the metadata missing from uv.lock.
+        # Binary wheels are more likely to, but may still require overrides for library dependencies.
+        sourcePreference = "wheel"; # or sourcePreference = "sdist";
+        # Optionally customise PEP 508 environment
+        # environ = {
+        #   platform_release = "5.10.65";
+        # };
+      };
+
+      # Extend generated overlay with build fixups
+      #
+      # Uv2nix can only work with what it has, and uv.lock is missing essential metadata to perform some builds.
+      # This is an additional overlay implementing build fixups.
+      # See:
+      # - https://pyproject-nix.github.io/uv2nix/FAQ.html
+      pyprojectOverrides = _final: _prev: {
+        # Implement build fixups here.
+      };
+
+      pkgs = nixpkgs.legacyPackages.x86_64-linux;
+      python = pkgs.python312;
+
+      # Construct package set
+      pythonSet =
+        # Use base package set from pyproject.nix builders
+        (pkgs.callPackage pyproject-nix.build.packages {
+          inherit python;
+        }).overrideScope
+          (
+            lib.composeManyExtensions [
+              pyproject-build-systems.overlays.default
+              overlay
+              pyprojectOverrides
+            ]
+          );
+
+    in
+    {
+      # Package a virtual environment as our main application.
+      #
+      # Enable no optional dependencies for production build.
+      packages.x86_64-linux.default = pythonSet.mkVirtualEnv "name-env" workspace.deps.default;
+
+      # This example provides two different modes of development:
+      # - Impurely using uv to manage virtual environments
+      # - Pure development using uv2nix to manage virtual environments
+      devShells.x86_64-linux = {
+        # This devShell uses uv2nix to construct a virtual environment purely from Nix, using the same dependency specification as the application.
+        # The notable difference is that we also apply another overlay here enabling editable mode ( https://setuptools.pypa.io/en/latest/userguide/development_mode.html ).
+        #
+        # This means that any changes done to your local files do not require a rebuild.
+        default =
+          let
+            # Create an overlay enabling editable mode for all local dependencies.
+            editableOverlay = workspace.mkEditablePyprojectOverlay {
+              # Use environment variable
+              root = "$REPO_ROOT";
+              # Optional: Only enable editable for these packages
+              # members = [ "hello-world" ];
+            };
+
+            # Override previous set with our overrideable overlay.
+            editablePythonSet = pythonSet.overrideScope editableOverlay;
+
+            # Build virtual environment, with local packages being editable.
+            #
+            # Enable all optional dependencies for development.
+            virtualenv = editablePythonSet.mkVirtualEnv "name-dev-env" workspace.deps.all;
+
+          in
+          pkgs.mkShell {
+            packages = [
+              virtualenv
+              pkgs.uv
+            ];
+            shellHook = ''
+              # Undo dependency propagation by nixpkgs.
+              unset PYTHONPATH
+
+              # Don't create venv using uv
+              export UV_NO_SYNC=1
+
+              # Prevent uv from downloading managed Python's
+              export UV_PYTHON_DOWNLOADS=never
+
+              # Get repository root using git. This is expanded at runtime by the editable `.pth` machinery.
+              export REPO_ROOT=$(git rev-parse --show-toplevel)
+            '';
+          };
+      };
+    };
+}