user interface - Python Execution Order with GUI -


i'm having issues following code. first time i'm working gui , it's been while since i've worked python well. when try execute solfield function button, yields no output.

from tkinter import * import math  master = tk()  n = float() = float()   def solfield():     pass    label_coils = label(text='number of coils per meter', textvariable=n) label_coils.grid() coils = entry(master) coils.grid()  label_current = label(text='current in amps', textvariable=i) label_current.grid() current = entry(master) current.grid()  calculate_button = button(text='calculate', command=solfield()) calculate_button.grid() label_bfield = label(text='b field in +z direction') label_bfield.grid() label_result = label(text='solfield') label_result.grid()   master.title('coil gun simulation') master.mainloop()   def solfield():     mu0 = math.pi*4e-7     solfield = mu0*n*i     print solfield

any other tips appreciated well, there more coding me do.

this has been solved. if interested, here code after several fixes made:

from tkinter import * import math  master = tk()  label_coils = label(text='number of coils per meter') label_coils.grid() coils = entry(master) coils.grid()  label_current = label(text='current in amps') label_current.grid() current = entry(master) current.grid()    def solfield():     mu0 = math.pi*4e-7     n = float(coils.get())     = float(current.get())     fieldmag = mu0*n*i     print fieldmag  calculate_button = button(text='calculate', command=solfield) calculate_button.grid() label_bfield = label(text='b field in +z direction') label_bfield.grid() label_result = label(text='solfield') label_result.grid()    master.title('coil gun simulation') master.mainloop()

the problem here:

calculate_button = button(text='calculate', command=solfield())

to pass function solfield command, use name:

calculate_button = button(text='calculate', command=solfield)

what you're doing calling function, , passing return value of function command.

since defined solfield above do-nothing function, return value none, you're telling calculate_button command=none, , it's doing nothing.

meanwhile, sethmmorton pointed out (but deleted):

you have 2 functions named solfield, , naming variable solfield in 1 of solfield functions. remove empty function (the 1 pass), , using different variable name in remaining function.

this isn't causing actual problem, it's adding confusion makes harder find problem. (for example, if hadn't included excess empty definition of solfield @ all, have gotten nameerror in incorrect line, have made things easier debug.)

putting together, should is:

  1. get rid of empty (pass-only) definition of solfield.
  2. move real implementation of solfield above point build gui.
  3. don't name local variable solfield within function.
  4. pass solfield, not solfield() command calculate_button.

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