Added clear kwarg to display()

[dsblank]

display() is a very useful function in the ipython kernel (especially now that it is in scope by default). However, many times that I use it, I also need clear_output(), and clear_output(wait=True). However, it is quite a pain to have to:

from IPython.display import clear_output

In addition, many user don't know about clear_output, nor the wait option.

This PR adds display(clear=True) with wait=True by default. If you want to clear it now rather than later, you can:

display(clear=True)
print() # forces the clear now!

[dsblank]

@martinRenou What do you think about this? Also, not sure why it failed... I think a formatting rule, but I couldn't get "dark" to re-format it.

[Carreau]

I have no objections with that; if it's ok with the xeus folks to make sure we don't have diverging implementation.
I'll take care of the reformatting.

[dsblank]

I must admit that I don't understand the consistency check with xeus. There are quite a few kernels that have "display" functions. Is there some project to try to keep some core functionality consistent across kernels? If so, metakernel should be in the loop.

Anyway, if you point me to the xeus implementation, I can make a PR there too.

[martinRenou]

Now that xeus-python depends on IPython there should not be any problem on our side :) It should work out of the box with this change.

[dsblank]

@Carreau I guess this is ready then?

[Carreau]

Rebased on master and applied autoformatting where linter was complaining.

[Carreau]

Test are passing, merging. Shis should be automatically backported and will thus be release at end of month.

[lumberbot-app]

Owee, I'm MrMeeseeks, Look at me.

There seem to be a conflict, please backport manually. Here are approximate instructions:

1. Checkout backport branch and update it.

$ git checkout 7.x
$ git pull

2. Cherry pick the first parent branch of the this PR on top of the older branch:

$ git cherry-pick -m1 bb21d60fffa7036c7f5827b479026b94748e2ffd

3. You will likely have some merge/cherry-pick conflict here, fix them and commit:

$ git commit -am 'Backport PR #12823: Added clear kwarg to display()'

4. Push to a named branch :

git push YOURFORK 7.x:auto-backport-of-pr-12823-on-7.x

5. Create a PR against branch 7.x, I would have named this PR:

"Backport PR #12823 on branch 7.x"

And apply the correct labels and milestones.

Congratulation you did some good work ! Hopefully your backport PR will be tested by the continuous integration and merged soon!

If these instruction are inaccurate, feel free to suggest an improvement.