Not every loop hands you a clean iterable to wrap -- sometimes you need to decide for yourself when and where progress has moved on. This step drops the wrapper from the previous step and drives a ProgressBar by hand.

.. demo:: tutorial/step2

The default spinner walks slowly around the rainbow as it rotates. The bouncing marker and counter also get their colours from the default widgets.

The previous step gave range(100) to progressbar.progressbar() and let it manage everything. Here, the loop opens the bar as a context manager with with progressbar.ProgressBar() as bar: and, on each pass through its own for loop, calls bar.update(i + 1) to report the new value itself. The with block starts the bar on entry and finishes it on exit, just as progressbar.progressbar() did implicitly in step 1. The difference is that this code decides when update() is called, so it works just as well when progress doesn't come from iterating a sequence at all.

Next: :doc:`step3`.