[NTG-context] TeX capacity exceeded - in Lua block - why?

[Hans Hagen]

On 7/16/2015 10:55 AM, Procházka Lukáš Ing. - Pontex s. r. o. wrote:
> Hello,
>
> On Thu, 16 Jul 2015 10:27:48 +0200, Hans Hagen <pragma at wxs.nl> wrote:
>
>> On 7/16/2015 10:20 AM, Procházka Lukáš Ing. - Pontex s. r. o. wrote:
>>> Hello,
>>>
>>> why this code:
>>>
>>> ----
>>> \def\GG{\ifmmode G_G\else$\GG$\fi}
>>
>> because in math mode \GG expands \GG which expands \GG ....
>
> I want to just pass G_G in math mode, so it seems to me that "\ifmmode
> G_G..." does the check.
>
> The macro should write G + "lower index G" for both math and non-math
> scope.

so

\def\GG{\ifmmode G_G\else$G\low{G}$\fi}

or

\def\GG{\mathematics{G_G}}

now you do a check in \GG and then call for \GG again so \GG again does 
a check etc etc ... you just enforce endless recursion

> And, in non math scope, the macro should just enclose itself by $...$
> (or \m{...})...
>
> And, this works well in TeX code:
>
> ----
> \def\GG{\ifmmode G_G\else$\GG$\fi}
>
> \starttext
>    \GG $\GG$
>    \startitemize[][]
>      \sym{\GG} \GG
>      \sym{$\GG$} $\GG$
>      \sym{\m{\GG}} \m{\GG}
>      \item End
>    \stopitemize
> \stoptext
> ----
>
> So how to rewrite the itemization into Lua?
>
>> maybe you mean:
>>
>> \def\GG{\ifmmode G_G\else$GG$\fi}
>
> ... Could be \def\GG{\ifmmode G_G\else$G_G$\fi}, too, but why not
> \def\GG{\ifmmode G_G\else$\GG$\fi} (seems to me be simpler as the macro
> definition - which may be more complicated - appears only once)?
>
> Lukas
>
>
>>> \starttext
>>>    \GG $\GG$ % OK
>>>    \startitemize[][]
>>>      \sym{\GG} \GG % OK
>>>    \stopitemize
>>>
>>>    \startluacode
>>>      context.startitemize()
>>>        context.sym([[\GG]])
>>>        context("Abc")
>>>      context.stopitemize()
>>>    \stopluacode
>>> \stoptext
>>> ----
>>>
>>> fails with:
>>>
>>> "
>>> ....
>>> tex error       > tex error on line 14 in file
>>> d://Lukas/Docs/Ull-Gra/Test/Abr.mkiv: ! TeX capacity exceeded, sorry
>>> [input stack size=10000]
>>>
>>>
>>> \GG ->\ifmmode G_G\else $\GG
>>>                               $\fi
>>> \GG ->\ifmmode G_G\else $\GG
>>>                               $\fi
>>> \GG ->\ifmmode G_G\else $\GG
>>>                               $\fi
>>> \GG ->\ifmmode G_G\else $\GG
>>>                               $\fi
>>> \GG ->\ifmmode G_G\else $\GG
>>>                               $\fi
>>> \GG ->\ifmmode G_G\else $\GG
>>>                               $\fi
>>> ....
>>> l.14   \stopluacode
>>> ....
>>> "
>>>
>>> I need to call "\GG" from within Lua, and the real macro name is created
>>> run-time (contrary to this MNWE; so to be \GG, \HH, \Fik etc. - the name
>>> is obtained from a Lua table as a string).
>>>
>>> I cannot understand why all TeX calls are OK but the problem appears in
>>> Lua block...
>>>
>>> Best regards,
>>>
>>> Lukas
>>>
>>>
>>>
>>>
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>>>
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>>>
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>>>
>>
>>
>
>


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