Implement Timer class with context management

Week06/timer_mehmet_balci.py

@@ -0,0 +1,80 @@
+import time
+
+
+class Timer:
+    # __slots__ reduces memory usage and speeds up attribute access
+    __slots__ = ("start_time", "end_time", "_running")
+
+    def __init__(self):
+        # Store start and end timestamps
+        self.start_time = None
+        self.end_time = None
+
+        # Indicates whether the timer is currently running
+        self._running = False
+
+    def __enter__(self):
+        # Automatically start the timer when entering context
+        self.start()
+        return self
+
+    def __exit__(self, exc_type, exc_val, exc_tb):
+        # Automatically stop the timer when exiting context
+        self.stop()
+
+        # Returning False ensures exceptions are not suppressed
+        return False
+
+    def start(self):
+        # Prevent starting an already running timer
+        if self._running:
+            raise RuntimeError("Timer is already running")
+
+        # Use high-resolution performance counter
+        self.start_time = time.perf_counter()
+
+        # Reset end time
+        self.end_time = None
+
+        # Mark timer as running
+        self._running = True
+
+        return self
+
+    def stop(self):
+        # Prevent stopping a timer that isn't running
+        if not self._running:
+            raise RuntimeError("Timer is not running")
+
+        # Record end time
+        self.end_time = time.perf_counter()
+
+        # Mark timer as stopped
+        self._running = False
+
+        return self
+
+    @property
+    def elapsed(self):
+        # Ensure timer has been started
+        if self.start_time is None:
+            raise RuntimeError("Timer has not been started")
+
+        # If still running, return current elapsed time
+        if self._running:
+            return time.perf_counter() - self.start_time
+
+        # Otherwise return total elapsed time
+        return self.end_time - self.start_time
+
+    def __repr__(self):
+        # Representation when not started
+        if self.start_time is None:
+            return "<Timer (not started)>"
+
+        # Representation when running
+        if self._running:
+            return f"<Timer running: {self.elapsed:.6f}s>"
+
+        # Representation when stopped
+        return f"<Timer stopped: {self.elapsed:.6f}s>"