Error: use of uninitialized value

Mojo
1

I’d like to create a list that I may need to add values to, but I’m getting an error when I try to append to it. “error: use of uninitialized value” - which I think means, I’ve declared the variable, but haven’t initialized it.

Here is the code (there may be other issues with the code, I’m still learning, but one problem at a time :slight_smile: )

@value
struct MountInfo:
    var dev_type: String
    var device: String
    var mount_point: String


def get_nfs_cifs_mounts() -> Optional[List[MountInfo]]:
    path = Path('/proc/mounts')
    var device_list: List[MountInfo] # I think I need to do something here to initialize it.

    try:
        with open(path, 'r') as _file:
            var contents_str: String = _file.read()
            var contents_list: List[String] = contents_str.split('\n')
            
            for line in contents_list:
                var clean_line = String(line[].strip()).lower()
                if clean_line.find('nfs') != -1 or clean_line.find('nfs4') != -1:
                    var device_type: String = 'NFS'
                    parts = clean_line.split()
                    if len(parts) >= 2:
                        _mnt = MountInfo(device_type, parts[0], parts[1])
                        device_list.append(_mnt) # Error is popping up on this line
                elif clean_line.find('cifs') != -1:
                    device_type = 'CIFS'
                    parts = clean_line.split()
                    if len(parts) >= 2:
                        _mnt = MountInfo(device_type, parts[0], parts[1])
                        device_list.append(_mnt)
        return device_list
    except:
        print('Unable to open ', path)
        return None

If I change the declaration line to:

var device_list: List[MountInfo] = []

I get: cannot implicitly convert 'ListLiteral[]' value to 'List[MountInfo]'

Is there a way to initialize an empty list as if to say, I may need to add things to you later, but for now you’re empty.

2

ListLiterals (the type associated with the syntax you’re trying to use for initialization) are very underbaked right now. You should initialize your list like so:
var device_list = List[MountInfo]()

3

That makes sense. Thank you!