[IPython-dev] Rich user_variable and user_expression.

Matthias BUSSONNIER bussonniermatthias at gmail.com
Sat Nov 17 07:23:01 EST 2012

Hi dev list, 

As you might be aware, IPython have a rich display and messaging protocol. 
The messaging one has been design before the display protocol.
Especially, user_variable and user_expression only allow to get string repr of object. 

This is one of the reason we might be considering extending the messaging protocol, 
And especially user_variable and user_expression to transmit not only the repr 
of result/variable but also the _repr_latex_ _repr_html_ ... etc.

One argument against this is that rich display is pretty expensive, so that we discourage 
moving huge amount of data through this channel especially if fronted do not use it. 

IMHO, when a piece of code use user_expression or user_variable, you could explicitly ask for a preferred representation.
So most representation should be opt-in. 

We'll be happy to have your thought about that if you use the messaging protocol in your applications.
Also this mail should be used as a starting point for us if we decide to draft a next version of the messaging protocol.



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