sharing variables between two scripts

[vishalsethia]

I was wondering if I declare a variable as global , can I share the same variable in a different file with the updated value. (ie) A global variable value to be used between different files without passing them within functions.


Say for eg.

Script 1

global foo = "sample"

def func1
   global foo
   foo = "updated sample"
   print foo 

print foo
func1 
x = script2.script2()
print foo

Script 2 (filename - script2)
------------

class script2:
     def __init__():
          global foo
          print foo
          foo = "Updated in Script2 "

Is there a better way in which I use variables among different files without declaring them as global ?

Thanks
--V

[bartonc]

It works like this:

# script1.py
a = 1 # this is module scope variable
def func1():
    pass    # here a function in script1 is defined

class myClass(object):
    pass    # difine a class

# script2.py
import script1
print script1.a

script1.func1()

myInst = script1.myClass()

[bartonc]

It works like this:

# script1.py
a = 1 # this is module scope variable
def func1():
    pass    # here a function in script1 is defined

class myClass(object):
    pass    # difine a class

# script2.py
import script1
print script1.a

script1.func1()

myInst = script1.myClass()

You can also (but this is discouraged)

# script2.py
from script1 import *
print a

or (this is better practice)

# script2.py
from script1 import myClass
myInst = myClass()

This is done to get constants, functions and classes. Actual variables always stay in the module where they are changed. This is part of what makes programming in python make sense. Globals are discourages as a generaly rule, but there are times when they are needed.

[bartonc]

I was wondering if I declare a variable as global , can I share the same variable in a different file with the updated value. (ie) A global variable value to be used between different files without passing them within functions.


Say for eg.

Script 1

global foo = "sample"

def func1
   global foo
   foo = "updated sample"
   print foo 

print foo
func1 
x = script2.script2()
print foo

Script 2 (filename - script2)
------------

class script2:
     def __init__():
          global foo
          print foo
          foo = "Updated in Script2 "

Is there a better way in which I use variables among different files without declaring them as global ?

Thanks
--V

By the way, welcome to the Python Forum on TheScripts.com. You'll learn to use code tags as you go along. There are a couple of places to find "Posting Guidelines". Just ask if you need help and keep posting,
Barton

[vishalsethia]

I tried to implement based on the previous comment, but it doesn't seem to serve to work. I am not sure what am I missing here ?

The output I get is

['234', '123']
['444', '233']
[]

I am not sure how do I achieve this ?
If either of the files update that global variable, wherever I print, it should have that updated value. Also I am not sure declaring global variables is a nice idea for sharing variables among files.

Script 1
--------------

from foo import MyClass

myinst = MyClass()
print myinst.alist
myinst.alist = ['444','233']
print myinst.alist
myinst.func1()

Script 2
------------

alist = []


class MyClass(object):
        alist = ['234','123']
        pass

        def func1(self):
                print alist
                pass

Thanks

[bartonc]

I tried to implement based on the previous comment, but it doesn't seem to serve to work. I am not sure what am I missing here ?
I am not sure how do I achieve this ?
If either of the files update that global variable, wherever I print, it should have that updated value. Also I am not sure declaring global variables is a nice idea for sharing variables among files.
Thanks

Yes, declaring global variables is not a nice idea for sharing variables among files. You are on the right track by using classes to hold variables. Keep playing with that and keep posting.

[bvdet]

I tried to implement based on the previous comment, but it doesn't seem to serve to work. I am not sure what am I missing here ?

The output I get is

['234', '123']
['444', '233']
[]

I am not sure how do I achieve this ?
If either of the files update that global variable, wherever I print, it should have that updated value. Also I am not sure declaring global variables is a nice idea for sharing variables among files.

Script 1
--------------

from foo import MyClass

myinst = MyClass()
print myinst.alist
myinst.alist = ['444','233']
print myinst.alist
myinst.func1()

Script 2
------------

alist = []


class MyClass(object):
        alist = ['234','123']
        pass

        def func1(self):
                print alist
                pass

Thanks

'alist' in Script2 is defined twice - first as a global variable and second as a class variable. 'func1' looks inside its scope first for alist. Not finding it, it looks in the global scope and finds an empty list '[]' to print.

class MyClass(object):
        alist = ['234','123']
        pass

        def func1(self):
                print self.alist
                pass

'func1' is now an instance method and finds the class variable 'alist' to print:
>>> ['234', '123']
['444', '233']
['444', '233']

I try to avoid global variables where possible.

[bvdet]

'alist' in Script2 is defined twice - first as a global variable and second as a class variable. 'func1' looks inside its scope first for alist. Not finding it, it looks in the global scope and finds an empty list '[]' to print.

class MyClass(object):
        alist = ['234','123']
        pass

        def func1(self):
                print self.alist
                pass

'func1' is now an instance method and finds the class variable 'alist' to print:
>>> ['234', '123']
['444', '233']
['444', '233']

I try to avoid global variables where possible.

Clarification - 'func1' now finds the class variable 'alist' to print. The global namespace for a function is always the module in which it is defined.
Script2:

alist = ['1', '2', '3']

class MyClass(object):
        alist = ['234','123']
        pass

        def func1(self):
                print self.alist
                pass

>>> import Script2
>>> Script2
<module 'Script2' from 'C:\SDS2_7.0\ma cro\Work In Progress\Script 2.py'>
>>> Script2.alist
['1', '2', '3']
>>> myinst
<Script2.MyClas s object at 0x00D66FF0>
>>> myinst.alist
['444', '233']
>>> myinst.func1()
['444', '233']
>>>

HTH :)

[vishalsethia]

Thanks .. that helped.