New Script

LoadingIcon/README.md

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+
+# Loading Icon
+
+When doing a lengthy calculation, instead of staring at a blank screen, the program runs a spinner to show that it's still working.
+In the threading example the spinner is running in a different thread, in the async example, the spinner is another task in the event loop.

LoadingIcon/async_spinner.py

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+import asyncio
+import itertools
+import sys
+
+
+async def spin(msg):
+    write, flush = sys.stdout.write, sys.stdout.flush
+
+    for char in itertools.cycle('|/-\\'):
+        status = char + ' ' + msg
+        write(status)
+        flush()
+        write('\x08' * len(status))
+
+        try:
+            await asyncio.sleep(0.1)
+        except asyncio.CancelledError:
+            break
+
+        write(' ' * len(status) + '\x08' * len(status))
+
+
+async def slow_function():
+    await asyncio.sleep(5)
+    return 42
+
+
+async def supervisor():
+    spinner = asyncio.ensure_future(spin('Thinking!'))
+    result = await slow_function()
+    spinner.cancel()
+    return result
+
+
+def main():
+    loop = asyncio.get_event_loop()
+    result = loop.run_until_complete(supervisor())
+    loop.close()
+    print('Answer:', result)
+
+
+if __name__ == '__main__':
+    main()

LoadingIcon/threading_spinner.py

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+
+import threading
+import itertools
+import time
+import sys
+
+
+class Signal:
+    go = True
+
+
+def spin(msg, signal):
+    write, flush = sys.stdout.write, sys.stdout.flush
+
+    for char in itertools.cycle('|/-\\'):
+        status = char + ' ' + msg
+        write(status)
+        flush()
+        write('\x08' * len(status))
+        time.sleep(0.1)
+
+        if not signal.go:
+            break
+
+        write(' ' * len(status) + '\x08' * len(status))
+
+
+def slow_function():
+    time.sleep(5)
+    return 42
+
+
+def supervisor():
+    signal = Signal()
+    spinner = threading.Thread(target=spin, args=('thinking!', signal))
+    spinner.start()
+    result = slow_function()
+    signal.go = False
+    spinner.join()
+    return result
+
+
+def main():
+    result = supervisor()
+    print('Answer:', result)
+
+
+if __name__ == '__main__':
+    main()