TI-84 Python programming – Introduction – simple Euro Calculator

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TI-84 Python edition – hybrid programming

The Texas Instruments TI-84 Plus CE-T calculator has a special edition called “Python Edition”
It’s easy to develop Python programs for this system. 
I’m developing like this:
I develop the programs like normal python programs on a PC with an editor (in my case PyCharm and Notepad++).
To be able to test the program on a PC (multi-platform, hybrid) I’ve made the following design.

1. conditional support for imports from TI libraries, like this:
​try:
    from ti_system import *
except Exception as e:
     print (“no module ti_system”)

2. read and write data wrapped in functions with a hybrid implementation
For reading data TI uses recall_list
For writing data TI uses store_list
On a “normal” system without the ti_system library this will not work.
So, I made wrapper functions with exception handling, e.g.

def saveeuro(ieuro):
    xlist=[]
    xlist.append(ieuro)
  try:
      store_list(“1”,xlist)
  except NameError as e:
      saveEuroToFile(ieuro)
  return

See github for the sourcecode (or see EUROCHF.py below):
​github.com/edleijnse/ti84python

EUROCHF.py
sample program to convert currencies (in sample from CHF TO EURO)
The EURO currency is stored and can be changed anytime.
On the TI-84 you can read (or set) the currency with STAT and L1 

try:
  from ti_system import *
except Exception as e:
    print ("no module ti_system")
def euro2chf(initeuro):
  print("")
  try:
     neweuro = float(input("new euro value? (" + '{:.2f}'.format(initeuro) + "): "))
  except Exception as e:
     neweuro=initeuro

  euro= neweuro

  print("euro: " + '{:.2f}'.format(euro))
  print("")
  eurocount=float(input("amount euros "))
  print("amount euros: ", eurocount)
  chf=euro*eurocount
  print ("costs in CHF: " + '{:.2f}'.format(chf))
  return neweuro

def getEuroFromFile():
    try:
       file1 = open("eurostore.txt","r")
       storedeuro = file1.read()
       storedeuro = int(storedeuro)
       file1.close()
    except Exception as e:
       storedeuro = .95
    return storedeuro
def geteuro():
    try:
        xlist=recall_list("1")
        storedeuro = float(xlist[0])
    except NameError as e:
        storedeuro=getEuroFromFile()
    except Exception as e:
        storedeuro = .83
    saveeuro(storedeuro)
    return storedeuro
def saveEuroToFile(iEuro):
    file1 = open("eurostore.txt","w")
    file1.write(str(iEuro))
    file1.close()
def saveeuro(ieuro):
    xlist=[]
    xlist.append(ieuro)
    try:
       store_list("1",xlist)
    except NameError as e:
       saveEuroToFile(ieuro)
    return

initeuro=geteuro()
while True:
  try:
    stopnow = input("stop program (1=y)? ")
    if stopnow == "1":
       break
    initeuro = euro2chf(initeuro)
    saveeuro(initeuro)
  except Exception as e:
    print(e)

LINKS TI-PYTHON articles

https://www.tomshardware.com/news/circuitpython-powers-ti-84-calculator

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