Spack info.print_text_info

Question

AttributeError: 'str' object has no attribute 'build_system_class'

I am getting this error when attempting to run this code. Does anyone know what is wrong?

import spack.cmd.info
import sys

pkg = sys.argv[1]
spack.cmd.info.print_text_info(pkg)

Answer 1

From what I have seen from your question and the documentation, I assume the following:

1. You are trying to use Spack API (https://spack.readthedocs.io/en/latest/spack.cmd.html?highlight=print_text_info#spack.cmd.info.print_text_info)
2. You are building some kind of automation on top of the spack package manager, I doubt it is a package.
3. You are using the sys package of Python (https://docs.python.org/3/library/sys.html)

The problem you have has nothing to do with Spack but rather with Python or object-oriented programming. You are fetching a string, sys.argv[1], representing a package name provided in the command-line and giving it to a method, print_text_info, which expects an object of PackageBase type, or its inheritances, e.g., AutotoolsPackage.

Python calls the method using string and calls a member of PackageBase type which doesn't exist for a string, resulting in the aforementioned error.

If you check the info.py of spack, you can see that it fails the first time it tries to call a method build_system_class.

def print_text_info(pkg):
    """Print out a plain text description of a package."""

    header = section_title(
        '{0}:   '
    ).format(pkg.build_system_class) + pkg.name
    color.cprint(header)

If you look at the info() method (which implements the spack info command) in spack.cmd.info, you can see how names are looked up to get package instances:

def info(parser, args):
    pkg = spack.repo.get(args.package)
    print_text_info(pkg)

So, to get the PacakgeBase instance to pass to print_text_info(), you just need to import spack.repo and call spack.repo.get(name) as above.