Restore the slime-presentation-streams contrib

[luismbo]

It was disabled due to issue #212. https://sourceforge.net/p/sbcl/mailman/message/33102884/ outlines how to reimplement it properly.

[luismbo]

@phmarek fixed some newer breakage here: phmarek@e3c3540 due to sbcl/sbcl@14c8a92

[luismbo]

@snuglas how likely do you think it would be for SLIME to have some way to hook into pretty printing? Would it help to send an e-mail to sbcl-devel (or similar) describing slime-presentation-streams's needs?

[scymtym]

Another data point for that discussion would be https://github.com/McCLIM/McCLIM/tree/master/Experimental/pprint.

I think it also tried to turn pieces of pretty print output into presentations.

CC @dkochmanski

[snuglas]

probably best to ask on sbcl-devel, even better if you can also propose some mechanism by which to achieve the outcome.

…

[luismbo]

@phmarek, @scymtym: are any of you inclined to propose an API and/or patch?

[scymtym]

@scymtym: are any of you inclined to propose an API and/or patch?

I don't have enough time at the moment, sorry.

[phmarek]

Well, why not take stassats idea from the ML? Or does that solve a different problem?

[luismbo]

@stassats has your idea matured in the past 4 years? :-)

[stassats]

Yes, it's prime for somebody (read not me) to implement it and integrate it into Slime.

[luismbo]

@stassats I wonder if it'd compose better to have make-pretty-stream be a generic function that dispatches on the target stream? That way we could add methods for SLIME streams and leave room for other prettiness hacks without setting a global variable.

[luismbo]

Hmm, probably too early for CLOS?

[stassats]

It's not too early for CLOS (i.e. when Slime is loaded). The target stream would have to be subclassed and methods are easily dynamically scoped.

[luismbo]

BTW, I recently noticed that swank-presentation-streams has two mechanisms for hooking into object printing, one of which is only used when in *use-dedicated-output-stream* mode that is much less intrusive and doesn't require hooking into make-pretty-stream. I think this explains how @phmarek is using this contrib when I had the impression that the contrib didn't work at all.

[luismbo]

@stassats sorry, I don't understand what you mean. I was thinking that the constructor for pretty-stream could be named %make-pretty-stream or something and a generic function make-pretty-stream would dispatch on the target stream and either call %make-pretty-stream (a default method provided by SBCL) or our make-pretty-slime-stream (via our own method). What did you have in mind?