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apps: calc: Rewrite the display and calculation engine

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Currently calculations such as 22/7 do not work correctly on the
simulator (which uses double precision floating point). Fix this
by explicitly truncating the strings when needed.

Additionally the current calculate() method has some problems when
the calculation cannot be evaluated since it will needlessly clear out
the calculation. Push calculate (and the exception handling) into the
caller and report errors using the vibration motor instead.

Finally we rename display_output() to the more idiomatic _update().

Signed-off-by: Daniel Thompson <daniel@redfelineninja.org.uk>
This commit is contained in:
Daniel Thompson 2020-12-28 14:41:37 +00:00
parent e570bf4f26
commit 21210c5c07
1 changed files with 8 additions and 26 deletions
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34
wasp/apps/calc.py
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@ -74,10 +74,13 @@ class CalculatorApp():
if (button_pressed == "C"):
self.output = ""
elif (button_pressed == "="):
self.output = self.calculate(self.output)
try:
self.output = str(eval(self.output.replace('^', '**')))[:12]
except:
wasp.watch.vibrator.pulse()
else:
self.output += button_pressed
self.display_output()
self._update()
def _draw(self):
draw = wasp.watch.drawable
@ -106,27 +109,6 @@ class CalculatorApp():
draw.string("<", 215, 10)
draw.set_color(wasp.system.theme('accent-hi'))
def display_output(self):
wasp.watch.drawable.fill(x=2,y=2,w=170,h=40)
if (self.output != ""):
if len(self.output) >= 10:
wasp.watch.drawable.string(self.output[len(self.output)-9:], 6, 14, width=170)
else:
wasp.watch.drawable.string(self.output, 6, 14, width=170)
def calculate(self,s):
equation = s
# Normal calculator stuff
for i in range(len(s)):
if (s[i] =="^"):
equation = s[:i] + "**"+s[i+1:]
elif (s[i] == ":"):
equation = s[:i] + "/"+s[i+1:]
try:
result = eval(equation)
except: # Error
result = ""
return str(result)
def _update(self):
output = self.output if len(self.output) < 12 else self.output[len(self.output)-12:]
wasp.watch.drawable.string(output, 0, 14, width=200, right=True)