IPEP 13: user-expressions and user-variables

[minrk]

The user-expressions and user-variables side effects in execute_requests are updated to use the rich-repr display data identical to a display_data message.

closes #2654

[Carreau]

I would be carefull in merging this one as it might break on some other project. For example it breaks the ability of the qtconsole to display the list of magics in its menu.

[minrk]

Thanks for the pointer - I've updated that code to use JSON, which should be cleaner now that user_expressions supports full display data.

[Carreau]

Thanks for the pointer - I've updated that code to use JSON, which should be cleaner now that user_expressions supports full display data.

Could not just %lsmagic be updated to return multiple representation instead of creating a lsmagic_json ?

[minrk]

The only potential issue I see with that is that %lsmagic prints rather than returns, so it's a functional change. I think it is probably better, though. @fperez would you object to %lsmagic returning data instead of just printing it?

[Carreau]

Also, I think this might affect emacs Ein client, and maybe spyder and canopy. Do we specifically ping those people or just let them discover?

[ccordoba12]

Spyder here: We don't use %lsmagic @Carreau, but it would be better for us that it returned its data instead of printing it, so in the future we could build a web page with it to show it in our Object Inspector .

[Carreau]

@ccordoba12 are you using user-expressions/user-variables already in some places, even if it's not for lsmagic ?

[ccordoba12]

@Carreau: Nope, first time I've heard of them. What's its purpose?

[Carreau]

Execute an expression/retrieve variable value alongside code execution in the kernel:
Explanation in the doc

That's what qtconsole use to ask the list of availlable magics in the kernel.
That's also probably what you would use if you had to implement a panel with the list of variable in the kernel.

[Carreau]

Would it make sens to have other magics converted like that ?

[minrk]

Would it make sense to have other magics converted like that?

it probably would, but I don't think that's relevant to this PR.

[Carreau]

It probably would, but I don't think that's relevant to this PR.

Just asking, just didn't wanted to open a new issue for that.

Ok to merge for me.

[minrk]

thanks, merging away, then.