From f512069fc7446087dff3041515dd6f55dc293f89 Mon Sep 17 00:00:00 2001
From: James Greenwood <jamey@greenwood.im>
Date: Sat, 30 Aug 2025 11:33:20 +0100
Subject: [PATCH] dry, black, basic type hints, catch ctrl-d and ctrl-c

---
 fifth.py | 103 ++++++++++++++++++++++++++-----------------------------
 1 file changed, 49 insertions(+), 54 deletions(-)

diff --git a/fifth.py b/fifth.py
index 161415f..0f6cda7 100644
--- a/fifth.py
+++ b/fifth.py
@@ -1,79 +1,65 @@
 import operator
 import readline
+from typing import Callable
+
 
 class FifthStack:
     def __init__(self):
-        self.stack = []
-        self.commands = {
-            'push': self.push,
-            'pop': self.pop,
-            'swap': self.swap,
-            'dup': self.dup,
-            '+': self.add,
-            '-': self.sub,
-            '*': self.mul,
-            '/': self.div,
+        self.stack: list[int] = []
+        self.commands: dict[str, Callable] = {
+            "push": self.push,
+            "pop": self.pop,
+            "swap": self.swap,
+            "dup": self.dup,
         }
-        self.binary_ops = {
-            '+': operator.add,
-            '-': operator.sub,
-            '*': operator.mul,
-            '/': operator.floordiv,
+        self.binary_ops: dict[str, Callable[[int, int], int]] = {
+            "+": operator.add,
+            "-": operator.sub,
+            "*": operator.mul,
+            "/": operator.floordiv,
         }
-    
+
     def _require(self, number, message):
         if len(self.stack) < number:
-            print(message)
+            print(f"ERROR: {message}")
             return False
         return True
-    
+
     def _get_binary_op(self, command):
         return self.binary_ops.get(command)
-    
+
     def _binary_op(self, operator):
         if not self._require(2, "two numbers required"):
             return
-        a, b = self.stack.pop(), self.stack.pop()
+        b, a = self.stack.pop(), self.stack.pop()
         try:
             self.stack.append(operator(a, b))
-        except Exception as e:
-            print(f"ERROR: {e}")
+        except ZeroDivisionError as e:
+            print(f"ERROR: division by zero")
             self.stack.extend([a, b])
-    
+
     def push(self, value):
         try:
             self.stack.append(int(value))
         except ValueError:
             print("ERROR: integer required")
 
-    def pop(self, _value):
+    def pop(self):
         if not self.stack:
             print("ERROR: stack empty")
             return
         self.stack.pop()
 
-    def swap(self, _value):
-        if not self._require(2, 'two numbers required'):
+    def swap(self):
+        if not self._require(2, "two numbers required"):
             return
         self.stack[-1], self.stack[-2] = self.stack[-2], self.stack[-1]
 
-    def dup(self, _value):
-        if self._require(1, 'stack empty'):
+    def dup(self):
+        if self._require(1, "stack empty"):
             self.stack.append(self.stack[-1])
 
-    def add(self, _value):
-        self._binary_op(self._get_binary_op('+'))
-
-    def sub(self, _value):
-        self._binary_op(self._get_binary_op('-'))
-
-    def mul(self, _value):
-        self._binary_op(self._get_binary_op('*'))
-
-    def div(self, _value):
-        self._binary_op(self._get_binary_op('/'))
-
-    def execute(self, command):
+    def execute(self, command: str):
         tokens = command.lower().strip().split()
         if not tokens:
             return
@@ -81,21 +67,30 @@ class FifthStack:
         command, argument = tokens[0], tokens[1] if len(tokens) > 1 else None
         function = self.commands.get(command)
 
-        try:
-            if function: function(argument)
-            else: print("ERROR: unknown command")
-        except:
-            print("ERROR: invalid command")
+        if function:
+            if command == "push":
+                function(argument)
+            else:
+                function()
+        elif command in self.binary_ops:
+            self._binary_op(self._get_binary_op(command))
+        else:
+            print("ERROR: unknown command")
+
 
 def main():
     fifth = FifthStack()
-    
-    while True:
-        print(f'stack is: {fifth.stack}')
-        command = input()
-        if command.lower() == 'exit':
-            break
-        fifth.execute(command)
 
-if __name__ == '__main__':
+    while True:
+        print(f"stack is: {fifth.stack}")
+        try:
+            if command := input().strip().lower() == "exit":
+                break
+            if command:
+                fifth.execute(command)
+        except (EOFError, KeyboardInterrupt):
+            break
+
+
+if __name__ == "__main__":
     main()