[nix0n]

I've implemented quite a few lying progress bars.

It's impossible to estimate total completion percentage when one part of the operation is CPU-bound, and another part is disk-bound.

(I haven't had to deal with network-bound operations, but I feel for those who do.)

Truth is probably possible, but more work than it's worth, when one part of the operation is O(n) and another part is O(m^2).

If the feature is a week late, it doesn't crash, the answers are right, and the operation completes in a reasonable amount of time, I'm moving on with my life.

[sellyme]

Completion percentage doesn't have to be measured in time. If you've completed the CPU-bound operations and are just starting disk-bound operations, it's totally fair to say "50% complete", even if you expect one to take much longer than the other.

Alternatively you could use multiple bars - one showing the number of distinct tasks to complete, and the other showing the estimated time progression of the current task. Ideally chuck an expandible debug log underneath it. You probably want to be implementing a debug log while developing to test the thing anyway, just leave it in there! A lot of installers use this kind of progress bar and I've always found them to be the most user-friendly.