self.erase = 0
def onOperator(self, char):
self.eval.shiftOpnd(self.text.get()) # push opnd on left
self.eval.shiftOptr(char) # eval exprs to left?
self.text.set(self.eval.topOpnd()) # push optr, show opnd|result
self.erase = 1 # erased on next opnd|'('
def onMakeCmdline(self):
new = Toplevel() # new top-level window
new.title('PyCalc command line') # arbitrary Python code
frm = frame(new, TOP) # only the Entry expands
label(frm, LEFT, '>>>').pack(expand=NO)
var = StringVar()
ent = entry(frm, LEFT, var, width=40)
onButton = (lambda: self.onCmdline(var, ent))
onReturn = (lambda event: self.onCmdline(var, ent))
button(frm, RIGHT, 'Run', onButton).pack(expand=NO)
ent.bind('
var.set(self.text.get())
def onCmdline(self, var, ent): # eval cmdline pop-up input
try:
value = self.eval.runstring(var.get())
var.set('OKAY')
if value != None: # run in eval namespace dict
self.text.set(value) # expression or statement
self.erase = 1
var.set('OKAY => '+ value)
except: # result in calc field
var.set('ERROR') # status in pop-up field
ent.icursor(END) # insert point after text
ent.select_range(0, END) # select msg so next key deletes
def onKeyboard(self, event):
pressed = event.char # on keyboard press event
if pressed != '': # pretend button was pressed
if pressed in self.Operators:
self.onOperator(pressed)
else:
for row in self.Operands:
if pressed in row:
self.onOperand(pressed)
break
else: # 4E: drop 'Ll'
if pressed == '.':
self.onOperand(pressed) # can start opnd
if pressed in 'Ee': # 2e10, no +/-
self.text.set(self.text.get()+pressed) # can't: no erase
elif pressed == '\r':
self.onEval() # enter key=eval
elif pressed == ' ':
self.onClear() # spacebar=clear
elif pressed == '\b':
self.text.set(self.text.get()[:-1]) # backspace
1472 | Chapter 19: Text and Language