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Re: Enhancement suggestion: prin1 extension mechanism
From: |
Stefan Monnier |
Subject: |
Re: Enhancement suggestion: prin1 extension mechanism |
Date: |
Sun, 14 Sep 2008 15:35:34 -0400 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/23.0.60 (gnu/linux) |
>> I fear it'd be difficult to make it work without incurring a significant
>> performance overhead.
> If the table is nil you could use the default hardcoded printer without
> lookups.
In many important cases (e.g. CL has been loaded), the table wouldn't be
nil, and performance should still be good.
> If the entries in the table can be accessed from Lisp code, we could
> remember the default print function for a type before installing a
> custom printer. E.g. if a vector doesn't have the special symbol in the
> first entry, we could call the previously remembered default printer
> instead of iterating manually over the vector. Recursive calls to print
> would again use the custom print function.
I don't know what you're talking about. I'd probably understand better
with a piece of code.
> It seems to me that, compared to testing for circularity, those table
> lookups would only introduce a minor slowdown.
Testing for circularity is indeed too slow right now. That should be
fixed as well.
> And if someone produces so much output the that it takes to long to
> print, he probably doesn't want to read it anyway :-)
But it's difficult for Emacs to find ou before it's too late.
Stefan