Pass variable between python scripts
Question:
I’m sure this is very simple but I’ve been unable to get it working correctly. I need to have my main python script call another python script and pass variables from the original script to the script that I’ve called
So for a simplistic example my first script is,
first.py
x = 5
import second
and my second script is,
second.py
print x
and I would expect it to print x but I get
NameError: name 'x' is not defined
I’m not sure if import is right way to achieve this, but if someone could shed light on it in a simple way that would be great!
thanks,
EDIT
After reading the comments I thought I would expand on my question. Aswin Murugesh answer fixes the import problem I was having, however the solution does not have the desired outcome as I can not seem to pass items in a list this way.
In first.py I have a list which I process as follows
for insert, (list) in enumerate(list, start =1):
'call second.py passing current list item'
I wanted to pass each item in the list to a second python file for further processing (web scraping), I didn’t want to do this in first.py as this is meant to be the main ‘scan’ program which then calls other programs. I hope this now make more sense.
Thanks for the comments thus far.
Answers:
use the following script:
first.py:
x=5
second.py
import first
print first.x
this will print the x value. Always imported script data should be referenced with the script name, like in first.x
When you call a script, the calling script can access the namespace of the called script. (In your case, first can access the namespace of second.) However, what you are asking for is the other way around. Your variable is defined in the calling script, and you want the called script to access the caller’s namespace.
An answer is already stated in this SO post, in the question itself:
Access namespace of calling module
But I will just explain it here in your context.
To get what you want in your case, start off the called script with the following line:
from __main__ import *
This allows it to access the namespace (all variables and functions) of the caller script.
So now your calling script is, as before:
x=5
import second
and the called script is:
from __main__ import *
print x
This should work fine.
Try use exec
Python3.5:
first.py
x=5
exec(open('second.py').read())
second.py
print(x)
You can also pass x by using:
x=5
myVars = {'x':x}
exec(open('second.py').read(), myVars)
Not sure if this is a good way.
To avoid namespace pollution, import the variables you want individually: from __main__ import x, and so on. Otherwise you’ll end up with naming conflicts you weren’t aware of.
Finally,
I created a package for Python to solve this problem.
Install Guli from PIP.
$ pip install guli
Guli doesn’t require installing any additional PIP package.
With the package you can
Guli can be used to pass between different Python scripts, between many processes or at the same script.
pass variables between main Process and another (Multiprocess) Process.
- Pass variables between different Python scripts.
- Pass variables between ‘Main Process’ and another (Multiprocess) Process.
- Use variables at the same script.
- Create / Delete / Edit – GuliVariables.
Example
import guli
import multiprocessing
string = guli.GuliVariable("hello").get()
print(string) # returns empty string ""
def my_function():
''' change the value from another process '''
guli.GuliVariable("hello").setValue(4)
multiprocessing.Process(target=my_function).start()
import time
time.sleep(0.01) # delay after process to catch the update
string = guli.GuliVariable("hello").get()
print(string) # returns "success!!!"
Hope I solved the problem for many people!
I’m sure this is very simple but I’ve been unable to get it working correctly. I need to have my main python script call another python script and pass variables from the original script to the script that I’ve called
So for a simplistic example my first script is,
first.py
x = 5
import second
and my second script is,
second.py
print x
and I would expect it to print x but I get
NameError: name 'x' is not defined
I’m not sure if import is right way to achieve this, but if someone could shed light on it in a simple way that would be great!
thanks,
EDIT
After reading the comments I thought I would expand on my question. Aswin Murugesh answer fixes the import problem I was having, however the solution does not have the desired outcome as I can not seem to pass items in a list this way.
In first.py I have a list which I process as follows
for insert, (list) in enumerate(list, start =1):
'call second.py passing current list item'
I wanted to pass each item in the list to a second python file for further processing (web scraping), I didn’t want to do this in first.py as this is meant to be the main ‘scan’ program which then calls other programs. I hope this now make more sense.
Thanks for the comments thus far.
use the following script:
first.py:
x=5
second.py
import first
print first.x
this will print the x value. Always imported script data should be referenced with the script name, like in first.x
When you call a script, the calling script can access the namespace of the called script. (In your case, first can access the namespace of second.) However, what you are asking for is the other way around. Your variable is defined in the calling script, and you want the called script to access the caller’s namespace.
An answer is already stated in this SO post, in the question itself:
Access namespace of calling module
But I will just explain it here in your context.
To get what you want in your case, start off the called script with the following line:
from __main__ import *
This allows it to access the namespace (all variables and functions) of the caller script.
So now your calling script is, as before:
x=5
import second
and the called script is:
from __main__ import *
print x
This should work fine.
Try use exec
Python3.5:
first.py
x=5
exec(open('second.py').read())
second.py
print(x)
You can also pass x by using:
x=5
myVars = {'x':x}
exec(open('second.py').read(), myVars)
Not sure if this is a good way.
To avoid namespace pollution, import the variables you want individually: from __main__ import x, and so on. Otherwise you’ll end up with naming conflicts you weren’t aware of.
Finally,
I created a package for Python to solve this problem.
Install Guli from PIP.
$ pip install guli
Guli doesn’t require installing any additional PIP package.
With the package you can
Guli can be used to pass between different Python scripts, between many processes or at the same script.
pass variables between main Process and another (Multiprocess) Process.
- Pass variables between different Python scripts.
- Pass variables between ‘Main Process’ and another (Multiprocess) Process.
- Use variables at the same script.
- Create / Delete / Edit – GuliVariables.
Example
import guli
import multiprocessing
string = guli.GuliVariable("hello").get()
print(string) # returns empty string ""
def my_function():
''' change the value from another process '''
guli.GuliVariable("hello").setValue(4)
multiprocessing.Process(target=my_function).start()
import time
time.sleep(0.01) # delay after process to catch the update
string = guli.GuliVariable("hello").get()
print(string) # returns "success!!!"
Hope I solved the problem for many people!