Function isPackageInstalled

buildtools/setup_python.go:265–308

isPackageInstalled checks if a Python package is already installed. This avoids frequent PyPI requests that could lead to IP blocking.

(packageName string, venvDir string)

// isPackageInstalled checks if a Python package is already installed.
// This avoids frequent PyPI requests that could lead to IP blocking.
func isPackageInstalled(packageName string, venvDir string) bool {
	libDir := filepath.Join(venvDir, expr.If(runtime.GOOS == "windows", "Lib", "lib"))
	if !fileio.PathExists(libDir) {
		return false
	}

	// Get package name without version.
	packageName = strings.Split(packageName, "==")[0]

	var packageDirPattern, distInfoPattern, eggInfoPattern string
	switch runtime.GOOS {
	case "windows":
		// Windows: Lib/site-packages/{packageName} and Lib/site-packages/{packageName}-*.dist-info.
		packageDirPattern = filepath.Join(libDir, "site-packages", packageName)
		distInfoPattern = filepath.Join(libDir, "site-packages", packageName+"-*.dist-info")
		eggInfoPattern = filepath.Join(libDir, "site-packages", packageName+"-*.egg-info")

	case "linux", "darwin":
		// Linux/Darwin: lib/python*/site-packages/{packageName} and lib/python*/site-packages/{packageName}-*.dist-info.
		packageDirPattern = filepath.Join(libDir, "python*", "site-packages", packageName)
		distInfoPattern = filepath.Join(libDir, "python*", "site-packages", packageName+"-*.dist-info")
		eggInfoPattern = filepath.Join(libDir, "python*", "site-packages", packageName+"-*.egg-info")

	default:
		panic("unsupported os: " + runtime.GOOS)
	}

	matches, err := filepath.Glob(packageDirPattern)
	if err == nil && len(matches) > 0 {
		return true
	}

	matches, err = filepath.Glob(distInfoPattern)
	if err == nil && len(matches) > 0 {
		return true
	}

	matches, err = filepath.Glob(eggInfoPattern)
	if err == nil && len(matches) > 0 {
		return true
	}

	return false
}

// getWindowsDefaultPythonVersion reads Python version from static TOML.
func getWindowsDefaultPythonVersion() string {