functools_cmp_to_key.py 文件源码

def compare_obj(a, b):
    """Old-style comparison function.
    """
    print('comparing {} and {}'.format(a, b))
    if a.val < b.val:
        return -1
    elif a.val > b.val:
        return 1
    return 0

# Make a key function using cmp_to_key()