takes 1 positional argument but 2 were given

Question

I would like to run a command line tool to run in a separate function and passed to the button click the additional command for this program but each time I get this as a response.

takes 1 positional argument but 2 were given

from tkinter import *
import subprocess


class StdoutRedirector(object):
    def __init__(self,text_widget):
        self.text_space = text_widget

    def write(self,string):
        self.text_space.insert('end', string)
        self.text_space.see('end')

class CoreGUI(object):
    def __init__(self,parent):
        self.parent = parent
        self.InitUI()

        button = Button(self.parent, text="Check Device", command= self.adb("devices"))
        button.grid(column=0, row=0, columnspan=1)

    def InitUI(self):
        self.text_box = Text(self.parent, wrap='word', height = 6, width=50)
        self.text_box.grid(column=0, row=10, columnspan = 2, sticky='NSWE', padx=5, pady=5)
        sys.stdout = StdoutRedirector(self.text_box)

    def adb(self, **args):
        process = subprocess.Popen(['adb.exe', args], stdout=subprocess.PIPE, shell=True)
        print(process.communicate())
        #return x.communicate(stdout)


root = Tk()
gui = CoreGUI(root)
root.mainloop()

the error

Traceback (most recent call last):
  File "C:/Users/Maik/PycharmProjects/Lernen/subprocessExtra.py", line 33, in <module>
    gui = CoreGUI(root)
  File "C:/Users/Maik/PycharmProjects/Lernen/subprocessExtra.py", line 18, in __init__
    button = Button(self.parent, text="Check Device", command= self.adb("devices"))
TypeError: adb() takes 1 positional argument but 2 were given
Exception ignored in: <__main__.StdoutRedirector object at 0x013531B0>
AttributeError: 'StdoutRedirector' object has no attribute 'flush'

Process finished with exit code 1

can some body help me

there is something wrong with **args

Answer 1

It is because you are providing it a positional argument here:

button = Button(self.parent, text="Check Device", command= self.adb("devices"))

command want's a callback function. and you are passing it the response from the adb method. (see here fore more: http://effbot.org/tkinterbook/button.htm)

when that line is being called, self.adb("devices") is being called. if you look at your definition of adb

def adb(self, **args):

You are only asking for 1 positional argument self and any number of keyword arguments **args then you are calling it self.adb("devices") with 2 positional arguments of self and "devices"

What you will need to do is have an intermediate method, if you want to have the adb method more general, or just put "devices" into the adb method.

edit

See also here: http://effbot.org/zone/tkinter-callbacks.htm See the section "Passing Argument to Callbacks"

edit 2: code example

If you do this, it should work:

button = Button(self.parent, text="Check Device", command=lambda:  self.adb("devices"))

and then change your function to a single * inlieu of a ** (keyword arg expansion) See here: https://stackoverflow.com/a/36908/6030424 for more explanation.

def adb(self, *args):
    process = subprocess.Popen(['adb.exe', args], stdout=subprocess.PIPE, shell=True)
    print(process.communicate())
    #return x.communicate(stdout)