Re: [PATCH] Unicode Lisp reader escapes

[Oliver Scholz]

Eli Zaretskii <address@hidden> writes:

>> Cc: address@hidden,  address@hidden,  address@hidden
>> From: Stefan Monnier <address@hidden>
>> Date: Thu, 04 May 2006 17:40:28 -0400
>> 
>> >> After all, it's there, it works, and as mentioned: there's no
>> >> evidence that the decoding time of \u escapes it ever going to need
>> >> to be fast.
>> 
>> > ??? inside the Lisp reader, everything needs to be fast, IMO.
>> 
>> Why?
>
> Because the Lisp reader is the backbone of the Lisp interpreter.
>
>> IMO the only things that need to be fast are those things whose
>> performance has a visible impact.  I see no evidence that there'll ever be
>> a case where the speed with which we can read \u escapes will matter.
>
> You don't need to see an evidence of a collapsing bridge to know that
> it must be several times stronger than any imaginable load that could
> ever be put on it.
>
> In other words, not everything is empirical; there's a thing called
> ``good engineering practice.''
>
> Sorry for being overly didactic, I'm sure you know all that.  I'm just
> amazed that such a fundamental issue needs evidence.

For the sake of peace: my opinion doesn't probably matter much, but
personally I believe that the changes necessary for a C implementation
of `decode-char' are local enough to be safe. I wouldn't like to
change anything in mule.el or utf-8.el---not even a defvar---, but
maybe I just could make the necessary symbols available to C in
syms_of_lread:

    Qutf_translate_cjk_mode = intern ("utf-translate-cjk-mode");
    staticpro (&Qutf_translate_cjk_mode);

    [...]

    Qutf_subst_table_for_decode = intern ("utf-subst-table-for-decode");
    staticpro (&Qutf_subst_table_for_decode);

    Qtranslation_hash_table = intern ("translation-hash-table");
    staticpro (&Qutf_subst_table_for_decode);


And then access them from my port of `decode-char's core functionality
like this:    
    
    SYMBOL_VALUE (Qutf_translate_cjk_mode)
    [...]
    Fget (Qutf_subst_table_for_decode, Qtranslation_hash_table)
  

[Well, in fact I already did in my copy of Emacs.]    

    
    Oliver
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