How can I toy with this .py file?

I'm learning Python just so I can tinker with the files from AIMA easily. I know Java and C++, but I find the AIMA code on the repositories to be too obfuscated. The Python code looks simpler and more elegant...yet, I don't know Python.

I wanna import the functions in search.py.

I tried creating a search2.py file like this:

import search

class Problem2(Problem):
    pass

on the folder where search.py is开发者_如何学JAVA and got:

~/aima/aima-python$ python search2.py
Traceback (most recent call last):
  File "search2.py", line 3, in <module>
    class Problem2(Problem):
NameError: name 'Problem' is not defined

Why is this?

---

When you import search, you define the name search, as a module created from executing search.py. If in there is a class called Problem, you access it as search.Problem:

import search

class Problem2(search.Problem):
    pass

An alternative is to define Problem with this statement:

from search import Problem

which executes search.py, then defines Problem in your file as the name Problem from the newly-created search module. Note that in this form, the name search is not defined in your file.

---

You have two options here:

1. Instead of import search, write from search import Problem

2. Instead of class Problem2(Problem), write class Problem2(search.Problem)

---

If class Problem is located in the search module, you have to import it either like that from search import Problem or use it like that:

import search

class Problem2(search.Problem):
    pass