Python gui - passing input to script

Question

I currently have a main python script (main.py) which reads input from a second script (input.py) which can be modified by a user. The user sets variables such as number of dimensions (ndim), number of points (npts) etc. in the second script and these are read into main.py using the following:

filename = sys.argv[-1]    
m = __import__(filename)

      ndim = m.ndim
      npts1 = m.npts1
      npts2_recorded = m.npts2_recorded

The script is executed by the following command:

python main.py input

I would like to replace input.py with a GUI. Tkinter seems a sensible place to start and I can see how to create a GUI to enable the user to set the various options that they would otherwise have set in input.py. However, I do not know how to pass this information to main.py from the GUI. Is there an equivalent to __import(filename)__ which can extract information from selections made by a user in the GUI, or is there another way of achieving the same effect.

A minimal (not) working example based on the answer below: This code creates the file example.txt but the text given to block1 does not get written to the file.

from Tkinter import *

def saveCallback():
  with open("example.txt",'w') as outfile:
    outfile.write(block1.get())

def UserInput(status,name):
  optionFrame = Frame(root)
  optionLabel = Label(optionFrame)
  optionLabel["text"] = name
  optionLabel.pack(side=LEFT)
  var = StringVar(root)
  var.set(status)
  w = Entry(optionFrame, textvariable= var)
  w.pack(side = LEFT)
  optionFrame.pack()
  return w

if __name__ == '__main__':
  root = Tk()

  block1 = UserInput("", "Block size, dimension 1")

  Save_input_button = Button(root, text = 'Save input options', command = saveCallback())
  Save_input_button.pack()
  root.mainloop()

Solution

Use a file for that, save selections in the GUI to a file(just like you did before with input.py) and then read the file.

So, in your main.py

1. Open the GUI
2. The preferences entered by to user to the file
3. Read the file as you did before.

The only drawback here is that you have to make sure in your main.py script that the GUI have been already closed. For that you can use the subprocess module, there are several function there you can use for block until the process returns or ends.

With this approach you just have to type:

python main.py

and somewhere inside main.py:

# The function call will wait for command to complete, then return the returncode attribute.
rcode = subprocess.call(['python', 'gui_input.py'])

Code sample to write the value of an Entry to a file.

import tkinter

top = tkinter.Tk()


def saveCallback():
    with open("example.txt", 'w') as outfile:
        outfile.write(e1.get())


e1 = tkinter.Entry(top)
b1 = tkinter.Button(top, text ="Save", command = saveCallback)

e1.pack(side=tkinter.LEFT)
b1.pack(side=tkinter.RIGHT)


top.mainloop()

Comments

[218]

Could you give some more details. I'm very new to tkinter. How for example do you save the GUI preferences. At the moment I am trying a simple example with a button and a function .get() to print the output from the options, but I don't get any output.

[Raydel Miranda]

By "save the GUI preferences" I meant: save the preferences entered by user in the GUI. You only need to have a button (lets called buttonSave) that when click on a function write the content of the Entry(ies) to a file.

[218]

Yes, I realised that. But at the moment, I'm unable to even print the entries to the terminal with a button press, let alone save them to a file.

[218]

Thanks for your answer. The minimal example you have given makes sense, however, I still cannot get this to work with my code - it creates the file example.txt when the button is pressed, but no content is written to this file. Somehow, python cannot read the user input to block1 or maybe there is an ordering issue?