CODEWITHSUNDEEP
pythonimportmodule
TakeS
TakeS

Reputation: 626

Python, init method in an imported file

I'm getting a little confused about importing methods from another file.

I'm writing a Python script that imports from python-automata. I've downloaded the file and in my ../Python/ directory, I have DFA.py and myfile.py stored.

In myfile.py I have this written on top:

import DFA

As I'm following what's written in the python tutorial, I assume that in myfile.py I can use any method defined in DFA.py. That file has a method called __init__ which takes in 5 arguments and initializes a DFA. Then I write this in myfile.py:

DFA.__init__(states, alphabet, delta(states, alphabet), start, accepts)

Where states, alphabet, delta, start, and accepts are all basic lists/functions that I have initialized in myfile.py.

But then when I try to run myfile.py, I get this error:

Traceback (most recent call last):
  File "myfile.py", line 21, in <module>
    DFA.__init__(states, alphabet, delta(states, alphabet), start, accepts)
TypeError: module.__init__() takes at most 2 arguments (5 given)

I'm not sure why it says it takes 2 arguments, when DFA.py defines it as taking in 5 arguments. In DFA.py, I see:

class DFA:
    def __init__(self, states, alphabet, delta, start, accepts):
    ...

It seems like a similar errors I encountered earlier (see Python import issue and Python classes and __init__ method) but I don't think that I need to deal with inheritance here.

Upvotes: 0

Views: 3908

Answers (3)

Benjamin Murphy
Benjamin Murphy

Reputation: 108

When you put in DFA.__init__(), you're calling the __init__ method for the entire module (I don't even know what that is defined as). You should use DFA.DFA.__init__(), which refers to the __init__ method of the DFA class within DFA.py, or use:

from DFA import *
DFA.__init__()

Upvotes: 0

Peter Sobot
Peter Sobot

Reputation: 2557

You're importing DFA as a module, but you want to import the class within it instead. Try:

from DFA import DFA

You can then implicitly call __init__ by calling the constructor on your DFA class:

DFA(states, alphabet, delta(states, alphabet), start, accepts)     
# ^ this calls __init__ on DFA

Upvotes: 4

user180100
user180100

Reputation: 

from DFA import DFA

a = DFA(states, alphabet, delta(states, alphabet), start, accepts)

EDIT: methods named __xx__ are not meant to be called directly.

Some reading: http://docs.python.org/tutorial/classes.html

Upvotes: 5

Related Questions