Python Forum

hello all ...
i need to call this variable ( filename )from function qassam() inside another fileex() ..
this is my code :

import os 
def qassam():
        filename = "/root/Downloads/scapy.txt"
        #return filename


def fileex():
    filename = qassam
    if os.path.isfile(filename):
        print("is there")
    else:
        print("else ... ")
        
fileex()

error :

Error:
Traceback (most recent call last):
  File "/tmp/ArpScanner/arp.py", line 15, in <module>
    fileex()
  File "/tmp/ArpScanner/arp.py", line 10, in fileex
    if os.path.isfile(filename):
  File "/usr/lib/python2.7/genericpath.py", line 37, in isfile
    st = os.stat(path)
TypeError: coercing to Unicode: need string or buffer, function found

Function variables are local to function. They cannot be shared.

options.
maybe have function return variable.

import os 
def qassam():
    filename = "/root/Downloads/scapy.txt"
    return filename
 
 
def fileex():
    filename = qassam()
    if os.path.isfile(filename):
        print("is there")
    else:
        print("else ... ")
         
fileex()

Make shared variables

import os 

class ShareVariables:
    filename = ""

def qassam():
    ShareVariables.filename = "/root/Downloads/scapy.txt"
 
 
def fileex():
    if os.path.isfile(ShareVariables.filename):
        print("is there")
    else:
        print("else ... ")

qassum()         
fileex()

My least favorite. Have global variable

import os 
filename = ""

def qassam():
    global filename
    filename = "/root/Downloads/scapy.txt"
 
 
def fileex():
    if os.path.isfile(filename):
        print("is there")
    else:
        print("else ... ")

qassum()         
fileex()

but how its work while its not global ??? i try to use return and its working :

import os

def qassam():
        filename = "/root/Downloads/scapy.txt"
        return filename


def fileex():
    filename = qassam()
    #x = filename
    print(filename)
    if os.path.isfile(str(filename)):
        print("is there")
    else:
        print("else ... ")
        
fileex()

Roughly. Low level stuff.
Anytime a function return a variable.
It is put on the stack.
Function closes.
Then stack item is assign to variable.

---

python bytecode.

import os
import dis

def qassam():
    filename = "/root/Downloads/scapy.txt"
    return filename


def fileex():
    filename = qassam()
    if os.path.isfile(filename):
        print("is there")
    else:
        print("else ... ")

dis.dis(fileex)

Output:
 10           0 LOAD_GLOBAL              0 (qassam)
              2 CALL_FUNCTION            0
              4 STORE_FAST               0 (filename)

 11           6 LOAD_GLOBAL              1 (os)
              8 LOAD_ATTR                2 (path)
             10 LOAD_METHOD              3 (isfile)
             12 LOAD_FAST                0 (filename)
             14 CALL_METHOD              1
             16 POP_JUMP_IF_FALSE       28

 12          18 LOAD_GLOBAL              4 (print)
             20 LOAD_CONST               1 ('is there')
             22 CALL_FUNCTION            1
             24 POP_TOP
             26 JUMP_FORWARD             8 (to 36)

 14     >>   28 LOAD_GLOBAL              4 (print)
             30 LOAD_CONST               2 ('else ... ')
             32 CALL_FUNCTION            1
             34 POP_TOP
        >>   36 LOAD_CONST               0 (None)
             38 RETURN_VALUE

You do need to call the first function at some point if you want to exploit it later.

One approach, rather than returning a value or using globals is to set an attribute:

import os 
def qassam():
        qassam.filename = "words.csv"
 
def fileex():
    filename = qassam.filename
    if os.path.isfile(filename):
        print("is there")
    else:
        print("else ... ")

qassam()         
fileex()