Diff Python objects by dotted path

diff_objects.py

import inspect
import argparse

from importlib import import_module
from difflib import unified_diff

# If Rich is available, use it to colorize the diff.
# NOTE: Users can also use other tools like `colordiff`
try:
    from rich.console import Console
    from rich.syntax import Syntax

    _RICH_AVAILABLE = True
except ImportError:
    _RICH_AVAILABLE = False


def import_object(dotted_str):
    """
    Attempt to import the longest valid module prefix.
    Then get the remaining attributes nested in that module.
    Example:
        dotted_str = "mypkg.mymodule.SomeClass.NestedClass.my_method"
    """
    parts = dotted_str.split(".")
    for i in reversed(range(1, len(parts) + 1)):
        try:
            obj = import_module(".".join(parts[:i]))
            for attr in parts[i:]:
                obj = getattr(obj, attr)
            return obj
        except ImportError:
            pass
    raise ImportError(f"Cannot import '{dotted_str}'")


def get_source(dotted_str):
    obj = import_object(dotted_str)
    return inspect.getsource(obj)


def parse_args():
    parser = argparse.ArgumentParser(
        description="Diff two Python objects via dotted paths"
    )
    parser.add_argument("obj1", help="e.g. mypkg.mymodule.SomeClass.my_method")
    parser.add_argument("obj2", help="e.g. mypkg2.mymodule2.OtherClass.other_method")
    return parser.parse_args()


def diff_objects(obj_path1, obj_path2):
    source1 = get_source(obj_path1)
    source2 = get_source(obj_path2)

    diff_lines = unified_diff(
        source1.splitlines(),
        source2.splitlines(),
        fromfile=obj_path1,
        tofile=obj_path2,
    )

    return diff_lines


def print_diff(diff_lines):
    diff_text = "\n".join(diff_lines)

    if _RICH_AVAILABLE:
        console = Console(force_terminal=True)
        syntax = Syntax(diff_text, "diff", theme="ansi_dark", line_numbers=False)
        console.print(syntax)
    else:
        print(diff_text)


def main():
    args = parse_args()
    obj_path1, obj_path2 = args.obj1, args.obj2
    diff_lines = diff_objects(obj_path1, obj_path2)
    print_diff(diff_lines)


if __name__ == "__main__":
    main()