So far everything works fine. The tests run and we are happy.
But many times while I’m writing the code I want to run the pars.py script directly from the command line or the IDE to check what I just wrote.
But this will raise a ModuleNotFoundError unless I change the import statement in pars.py to:
from lexicon import scan
But of course this will then raise the error when I tried to run the tests.
Is there a way to keep both options available? (Run the tests successfully and also be able to run the scripts directly in the shell)
I tried changing all the parser for pars but the issue persists.
I think I am not understanding completely the import statement rules, and I might not be explaining my doubt correctly.
The tree now looks like this:
The file pars.py imports the function scan from the module lexicon contained in the same folder.
In order for nosetests to work, the import looks like this:
from ex48.lexicon import scan
My question is if there is a way I can write the import statement so I would be able to do this:
ex48/ex48 $ python pars.py
and not get the error ModuleNotFoundError: No module named ‘ex48’
Oh, I think I got what you said about where to be to run the tests, you also mention it several times in the book
So, to run nosetests I always do it from above the ex48 and tests directories. And this works fine.
My problem appears when I want to run just the file pars.py (not its tests)
Since this file imports from another file, and the import statement is like we see above I completely understand that the program will not find another folder ex48 to go inside.
But when I change the import statement to
from lexicon import scan
Then, the nosetests won’t work.
I’m clearly missing something but I’ve tried many different ways and I still can’t figure out what’s wrong.
Ok, now you should be a the top above your ex48. To be sure that’s true THIS SHOULD FAIL:
cat ex48/lexicon.py
If that works then you ARE NOT IN THE RIGHT SPOT. cd …
So you should be able to do this:
ls ex48
And only see ex48 and tests.
Now, do this:
mv ex48 to myex48project
Now, cd into that directory:
cd myex48project.
Your directory should now be like this:
myex48project/
^------------------------------ you are here
ex48/ <----- this is where python gets everything
__init__.py
lexicon.py
pars.py
tests/
__init__.py
lexicon_tests.py
pars_tests.py
Ok, now change your code back to this:
from ex48.lexicon import scan
Then, explain to me what that’s doing, in steps, given that you have now named your project myex48project, so how does the above code work?
Ok, first of all, thanks for taking your time doing this step by step course for me
I made the changes.
So, I am positioned inside myex48project/
The import statement of your last comment will make python:
First look inside ex48/
Then look inside the file lexicon.py
And then look for scan inside that file, which in this case is a function
With this configuration nosetests runs correctly.
My problem was when I tried to run from the same location
$ python ex48/pars.py
This would give me the error
ModuleNotFoundError: No module named 'ex48'
Which I makes sense, because there’s no module ex48 in the same location than the file pars.py
The program should go up one level for that import statement to make sense.
Then I tried again export PYTHONPATH=. and now it worked!
I had read other entries in the forum where you suggested this and you even mentioned it in the book, but my mistake was to always call that code in random places. Now I understand better that I have to call it while positioned in the folder that I want to add to the PYTHONPATH.
In this case I called it from myex48project/ and after that I was able to do
$ python ex48/pars.py
and the code ran correctly.
So, am I in the correct path?
Is this the way I should always structure my code and tree?
And should I always use PYTHONPATH to add the location and run my code from there (in this case _myex48project/)?
