[luatex] Getting the extra primitives?

[Joseph Wright]

On 16/02/2010 15:43, luigi scarso wrote:
> On Tue, Feb 16, 2010 at 1:14 PM, Joseph Wright<joseph.wright at uea.ac.uk>  wrote:
>> Hello all,
>>
>> Thanks for the help thus far. I'm now stuck on the next step, I'm afraid.
>> With a file to build a format something like:
>>
>> \catcode `\{ = 1 \relax
>> \catcode `\} = 2 \relax
>> \catcode `\# = 6 \relax
>> \catcode `\^ = 7 \relax
>> \catcode `\^^I = 10 \relax
>> \begingroup\expandafter\expandafter\expandafter\endgroup
>> \expandafter\ifx\csname directlua\endcsname\relax
>> \else
>>   \long\def\pdfstrcmp#1#2{%
>>     \directlua
>>       {%
>>         joseph.strcmp("\luaescapestring{#1}","\luaescapestring{#2}")%
>>       }%
>>   }
>>   \directlua
>>     {
>>       tex.enableprimitives('',tex.extraprimitives ())
>>       module("joseph",package.seeall)
>>       function strcmp(A, B)
>>         if A == B then
>>           tex.write("0")
>>         elseif A<  B then
>>           tex.write("-1")
>>         else
>>           tex.write("1")
>>         end
>>       end
>>     }
>> \fi
>> \dump
>>
>> If I then try building the format and using it, with something as simple as
>>
>> \ifnum\pdfstrcmp{a}{b}=0\TRUE\else\FALSE\fi
>>
>> I get:
>>
>> ! LuaTeX error<\directlua>:1: attempt to index global 'joseph' (a nil
>> value)
>> stack traceback:
>>         <\directlua>:1: in main chunk.
>> \pdfstrcmp ...ring {#1}","\luaescapestring {#2}")}
>>
>> <*>  \ifnum\pdfstrcmp{a}{b}
>>                           =0 \TRUE\else\FALSE\fi
>> ?
>>
>> Obviously I'm still getting something wrong.
>
> joseph  = joseph  or { }
>
> Next you need to implement strcmp function
>
> function joseph.strcmp(A,B)
> -- your implementation here

Further testing suggests the issue may be slightly different to my 
original explanation. As far as I can tell, if I use \pdfstrcmp as 
defined above during the format-creation process then all is fine (for 
example if I just stick \pdfstrcmp{a}{a} just before \dump): no errors. 
However, if I try to use if after making a format then I get the error 
as described. The conclusion is that the lua part of the set up does not 
survive the format-creation process. This seems to be very odd: am I 
getting something wrong? After all, the whole point of a format is that 
it is a pre-compiled and self-contained entity.
-- 
Joseph Wright