[tex-hyphen] Loading patterns twice, OT1 and apostrophe

[Taco Hoekwater]

Arthur Reutenauer wrote:
>>                   I've been thinking: Perhaps the final solution is to
>> do away with \lccode and \uccode completely and instead base the
>> system on unicode properties?
> 
>   You don't say :-)

Well, there is a downside also: an interface to the unicode properties
would have to be written too, lest we loose flexibility. TeX users
are used to being able to modify everything, so a static database
won't do.

>                                                 iniTeX doesn't want
> duplicate patterns.  It's one of the biggest problems we had to deal
> with since the beginning, but what is the rationale behind this
> no-duplicate policy?  

I suspect this is meant to capture:

    \input hyphen
    ....
    \input hyphen

At least for me, variant forms of double-loading of files have been
the main reason for the occurrence of that particular error.

Knuth generally generates an error when an irregularity is encountered
that is caused by the user, almost(?) nothing is silently ignored, even
if he knows a suitable default fallback. Many of such cases would be a
warning message only in modern programs, without the need for user
interaction.

>   The irony here is that LuaTeX doesn't complain about duplicate
> patterns anymore since the hyphenation-handling code moved over to
> libHnj last October, and part 43 of the original TeX code disappeared
> entirely; Taco, can you comment about that?

I could have added such testing code, but it seemed a bit pointless.
Duplicate patterns are harmless after all, it just wastes a few CPU
cycles.

Best wishes,
Taco