Tkinter code (with pmw) executing to soon please help

[Eric_Dexter at msn.com]

Instead of creating my buttons and waiting for me to press them to
execute they are executing when I create them and won't do my callback
when I press them..  thanks for any help in advance

button[num] = Tkinter.Button(frame,text =  returnstring,
command=callback(returnstring))#

this line executes on creation

my output on startup is (should output when I choose an option)

1 String pad
10 Chorus
25 Reverb
30 Mixer


The buttons do label correctly.






title = 'csd instrument list'

# Import Pmw from this directory tree.
import sys
sys.path[:0] = ['../../..']

import Tkinter
import Pmw
import csoundroutines

class Demo:
 def __init__(self, parent):
    frame = Tkinter.Frame(parent)
    frame.pack(fill = 'both', expand = 1)

    button = {}

    instr = [[]]
    instr = csoundroutines.csdInstrumentList2(sys.argv[1])

    num = 0          #instr_number

    buttonBox = Pmw.ButtonBox(parent)
    for i in range(0, len(instr.instrnum)):
        num += 1
        returnstring = instr.instrnum[i] +' '+ str(instr.comments[i])
        #printstring = zz + x[num]
        button[num] = Tkinter.Button(frame,text =  returnstring,
command=callback(returnstring))#kinter.Buttonstr(x[0]) + ' ' + x[1])# +
comments)
        button[num].pack()
        #returnstring = zz
        button[num].grid(column=num, row =
0)#,command=callback(returnstring))
        #button[num].pack()



    frame.grid_rowconfigure(3, weight=1)
    frame.grid_columnconfigure(3, weight=1)
    frame.pack()
def callback(text):
    print text
######################################################################

# Create demo in root window for testing.
if __name__ == '__main__':
    global filename
    filename = (sys.argv[1])
    root = Tkinter.Tk()
    Pmw.initialise(root)
    root.title(title)

    exitButton = Tkinter.Button(root, text = 'Exit', command =
root.destroy)
    exitButton.pack(side = 'bottom')
    widget = Demo(root)
    root.mainloop()

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