CODEWITHSUNDEEP
python
sanjay
sanjay

Reputation: 717

Python importing global variables inconsistent behaviour

I'm having trouble importing a variable from a different python file to my current one. I know this has been asked several time previously and I have tried almost all those solutions, but no use.

In file top.py:

import sys, getopt, pdb
import argparse

import my_parser

my_parser.start_parse(6)
my_parser.in_out(2)
print "info: ",my_parser.verilog_inps
print "N1 data: ",my_parser.ckt_data["N1"]

In file parser.py (the first few lines only):

   from collections import defaultdict

ckt_data = {}
global verilog_inps
verilog_inps = []
global verilog_outs
verilog_outs = []
global levels
levels = []
level_dict = defaultdict(list)

class ckt_elements:
    delay = 0
    inp_ = {}
    out_ = {}
    level = 0
    change = False
    prev = {}
    typ_ = ""

def start_parse(a):
    ckt_data["N1"] = a

def in_out(a):
    verilog_inps = [a,a+1,a+2]

The strange thing is that I am able to access some variables and I am not able to do so for others (I declared the inaccessible ones global to see if that helps but no)

The aforementioned global variables are being modified in functions in parser.py.

So, my question: Why this strange behaviour? Am I doing something wrong? Using python 2.7

Please let me know if the question is not clear enough (I am at a loss to explain this better)

EDIT

I have solved the issue I am facing by using a global definition file. In a separate file, I have declared the variables and then imported the file into all relevant files. (using import globals)

In any case, I am very curious to know what was wrong with my previous approach.

Upvotes: 0

Views: 320

Answers (1)

user2357112
user2357112

Reputation: 280207

The problem is that this function:

def in_out(a):
    verilog_inps = [a,a+1,a+2]

don't actually affect the global verilog_inps variable. It's assigning to a local. You need to put the global declaration inside each function where you want to assign to the global variable:

def in_out(a):
    global verilog_inps
    verilog_inps = [a,a+1,a+2]

or assignments inside a function will cause the Python bytecode compiler to create a local variable with the same name and target the assignment to that variable.

Upvotes: 1

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