ETA does not honor empty `format_finished`

[SimonLammer]

ETA does not honor empty `format_finished`

[wolph]

That is intended behaviour to be honest :)

The reason for always requiring a formatstring is consistency in spacing. With an empty formatstring it would move the other stuff in the progressbar around.

You can work around it by using a space ' ' or an invisible character such as '\x00'

[SimonLammer]

@wolph I'm not sure I understand. Could you give an example where an empty-string result of ETA would "move the other stuff in the progress bar around"?

[wolph]

Just take a look at this code:

import time
import progressbar


bar = progressbar.ProgressBar(widgets=[
    progressbar.ETA(format_finished=' '),
    ' Some text here ',
    progressbar.Bar(),
])

for i in bar(range(5)):
    bar.update(i)
    time.sleep(0.1)

time.sleep(1.00)

The output looks something like this:

ETA:   0:00:00 Some text here |#########                                      |
ETA:   0:00:00 Some text here |##################                             |
ETA:   0:00:00 Some text here |############################                   |
ETA:   0:00:00 Some text here |#####################################          |
  Some text here |############################################################|

As you can see, the text moves and the bar becomes much wider suddenly. That can be a bit confusing :)

[SimonLammer]

I see.
However, this also happens when setting format_finished-' ' which you suggested previously.

import progressbar
for value in progressbar.progressbar(
    [1],
    widgets=[
        "Foo",
        progressbar.ETA(
            format_finished=" ",
        ),
        "Bar",
    ],
):
    print()

FooETA:  --:--:--Bar
Foo Bar

Similarly, the invisible character you suggested also does not preserve ETA's output length (format_finished="\x00"):

FooETA:  --:--:--Bar
FooBar

This behaviour may look subpar, but that's a subjective notion. Some users may want to have it that way, some may not.
If those two options you suggested don't preserve the output length of ETA, why should explicitly setting format_string=""?

[wolph]

Oops... didn't notice your reply.

It actually does work in your example, in both cases :)
The reason that it doesn't appear to work is because you're not seeing the format_finished here but the format_not_started. The progressbar overwrites the current line and with the print() statement you're creating a new line so the old line won't be overwritten.

If you replace the print() with pass you'll see the proper output

If you want to use print statements in your code I would suggest enabling output redirection: https://github.com/wolph/python-progressbar#combining-progressbars-with-print-output