Proper way to pass variable with buttons

[murjam]

Hello

This is my first post on this forum. I have found that this place seems to have lot of knowledgeable people when it comes to Python. Anyway I'm quite new to GUI programming and I'm not exactly having a huge problem but I'm more interested about how to make my code prettier and proper.

Issue is that I have defined this class where I have three buttons that all call the same function/subroutine/def but with each button I would like to pass different variable.. in this case a number.

I found a working solution and I have also tried to reduce the amount of code with putting the whole thing in loop.. not using lambda: self.cVid("2") but lambda: self.cVid(length) and then repeating "length" with different numbers like length = "2" , length = "3" etc. Basically everything I try besides this working code results in only the last number being passed.. doesn't matter which button I press.

I understand that it is somehow related to tkinter loop but I have no idea how to handle this situation to make the code little bit more compact and not repeat this function definition for buttons each time:

buttonContainer = lambda: self.cVid("2")

class chooseVideoFiles:
	def __init__(self):
		canv = self.root = Toplevel(root)
		canv.geometry("+150+250")
		title = Label(canv, text = "Select 3 videos with specified or a bit longer length", font = ("Helvetica", 10, "bold")).grid()
		buttonContainer = lambda: self.cVid("2")
		Button(canv, text = "2 minutes", command = buttonContainer).grid(padx = 3, pady = 5, row = 1, column = 0, sticky = W)
		Label(canv, text = "Line 1").grid(padx = 85, pady = 5, row = 1, column = 0, sticky = W)
		buttonContainer = lambda: self.cVid("3")
		Button(canv, text = "3 minutes", command = buttonContainer).grid(padx = 3, pady = 5, row = 2, column = 0, sticky = W)
		Label(canv, text = "Line 2").grid(padx = 85, pady = 5, row = 2, column = 0, sticky = W)
		buttonContainer = lambda: self.cVid("5")
		Button(canv, text = "5+ minutes", command = buttonContainer).grid(padx = 3, pady = 5, row = 3, column = 0, sticky = W)
		Label(canv, text = "Line 3").grid(padx = 85, pady = 5, row = 3, column = 0, sticky = W)
	def cVid(self,length):
		chooseVideoFile(length)

Maybe somebody who has had to deal with similar situation knows how I should put this to rest.

[vegaseat]

The first thing that sticks out like a sore thumb is that you are using tabs for indentations. It makes for ugly and troublesome code. Use the standard 4 spaces for indents like most people do.

[woooee]

I prefer to bind the button to a function that returns the desired variable, but it is somewhat personal preference.

from Tkinter import *

class ChooseVideoFiles:
    def __init__(self, root):
        canv = Toplevel(root)
        canv.geometry("+150+250")
        title = Label(canv, 
              text = "Select 3 videos with specified or a bit longer length",
              font = ("Helvetica", 10, "bold")).grid()
        self.buttons(canv)
        exit = Button(canv, text='Exit', command=top.quit).grid(row=5,column=0)

    ##-------------------------------------------------------------------         
    def buttons(self, canv):
        b_row=1
        b_col=0
        parameter_list = [ [2, "2 minutes", "Line 1"], \
                           [3, "3 minutes", "Line 2"], \
                           [5, "5+ minutes", "Line 3"] ]

        for param in parameter_list:
            b = Button(canv, text=param[1])
            b.grid(padx=3, pady=5, row=b_row, column=b_col, sticky=W)
            lab = Label(canv, text=param[2]).grid(padx=93, pady=5, 
                        row=b_row, column=b_col, sticky=W)

            def handler ( event, self=self, button_num=param[0] ):
                return self.cb_handler( event, button_num )
            b.bind ( "<Button-1>", handler )

            b_row += 1

    ##----------------------------------------------------------------
    def cb_handler( self, event, cb_number ):
        print "cb_handler", cb_number                

top = Tk()
CV = ChooseVideoFiles(top)
top.mainloop()

[murjam]

thank for your solution woooee, it is definitely something to work with although I'm still open to other alternatives too.

@vegaseat had no idea about this.. I figure Python writers are the most space key damaging programmers in the world :D

I doubt I'm able to unlearn it though.. not that hard to mass convert fortunately.

[TrustyTony]

You do not need to push even tab most times as reasonable editors know Python indention style, even 4 spaces is the default tab width. Mostly I hit this isssue when I try code in IDLE command line and want to copy it over to my program file.