PanelCallbackHandler design principle

[MarcSkovMadsen]

yesterday I changed the PanelCallBackHandler handler to also output the final response from the agent.

The change is marked below.

I can see that Streamlits Callback handler does not write the 'output'. The user/ developer have to manually do this.

I'm thinking that maybe it was a mistake by me to change this. What do you think @ahuang11 ?

[ahuang11]

Right if users type return / yield in the callback, it would duplicate the results.

At the same time, all of the streaming from Langchain does not require any yield/return so if users use return, its also semi inconsistent.

One last point to consider is the tool usually reports the final answer.

[MarcSkovMadsen]

I'm more and more convinced it was a mistake. The CallbackHandler should be seen as something you attach to debug and can remove again. You should not change what else you do.

The code in the callback function should be

pn_cb = pn.chat.langchain.PanelCallbackHandler(instance=instance)
response = state.pandas_df_agent.run(contents, callbacks=[pn_cb])
return response

not

pn_cb = pn.chat.langchain.PanelCallbackHandler(instance=instance)
response = state.pandas_df_agent.run(contents, callbacks=[pn_cb])

I will make a PR to revert including updating the example notebooks. Then we can discuss from there.