CODEWITHSUNDEEP
pythonoopobject
Alex
Alex

Reputation: 903

Failing hard at OOP in python

This represents a simple class, that I have made to try and practice OOP.

import csv
import logging


class LoaderCSV:

    def __init__(self, file):
        self.file = file

        if file is None:
            logging.warning('Missing input file.')

    def load(self):
        with open(self.file) as f:
            holder = csv.reader(f)
            file_data = list(holder)

        return file_data

What happens is when I call this class with:

data = LoaderCSV.load(input_file)

I get 

line 14, in load 
with open(self.file) as f:
AttributeError: 'str' object has no attribute 'file'

I must be messing something up, but can't understand what. My previous attempt worked just fine this way. I just don't understand why

self.file

does not pass the value, assigned to the argument, when it is defined under __init__

Upvotes: 0

Views: 84

Answers (3)

iBelieve
iBelieve

Reputation: 1544

The problem is you're calling an instance method as a static method, so your filename is being passed in instead of self. The proper way to do this would be like:

loader = LoaderCSV(input_file)
data = loader.load()

This will pass in loader as the self parameter, allowing you to access the file name in the object's file field.

Check out the Python documentation on classes for more information.

Upvotes: 2

John Kugelman
John Kugelman

Reputation: 362167

You need to create the LoaderCSV object first, then call the load method on that object.

loader = LoaderCSV(input_file)
data = loader.load()

Upvotes: 1

khelwood
khelwood

Reputation: 59240

The way to use the instance method load is to make an instance of your class, and then call the method on that class. Like this:

myloader = LoaderCSV(input_file)
data = myloader.load()

or succinctly:

data = LoaderCSV(input_file).load()

Upvotes: 0

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