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Jason Anders
Treehouse Moderator 145,859 PointsDoes importing also import other imports?
When Kenneth Love creates the Combat class (combat.py) he imports random.
Then in the Monster class (monster.py) he imports `from combat import Combat'. (at about 3:10 in the video).
My question is... in combat.py, random has been imported. In monster.py, random has also been imported and then on another line, Combat is imported. So in monster.py, do we still need to import random or will that come with the Combat import?
4 Answers
Chris Freeman
Treehouse Moderator 68,425 PointsIn addition to what Jeff Wilton said, if monster.py had used the not-recommended import style from combat import *, then the import would grab everything from combat including its imports. This is dangerous because then monster.py would be relying on implicit importing of modules existing in another file. If combat.py changes, and removes its import of random, monster.py could break if it required random. Best to explicitly import everything you need in each file. "Explicit is better than Implicit!"
Jeff Wilton
16,646 PointsYou need to explicitly import anything that will be used in that file, otherwise it will throw an error at runtime.
NameError: name 'random' is not defined
MOD NOTE: Changed to Answer so it may be upvoted / marked as Best Answer.
Kenneth Love
Treehouse Guest TeacherYou should use explicit imports everywhere. DO THIS
However, just to add to the fun of the thread, let's assume we have:
monster.py
import random
class Monster:
....
other_file.py
import monster
hydra = monster.Monster()
In other_file.py, I can use monster.random to get access to the random library. That said, this is highly breakable and probably shouldn't be done in 99.9999999% of cases.
Maxwell Hunter
Python Web Development Techdegree Graduate 29,640 PointsYes, you would still need to
import random
because in the video, he doesn't import the whole combat.py file. He only picked out Combat (a function) from combat (the python document); he didn't actually import the entire file with the import already in it.
but like Chris said, "Explicit is better than Implicit!"