[NTG-context] Dig out contents of the TeX macro using Lua

Hans Hagen pragma at wxs.nl
Wed Jul 15 09:01:49 CEST 2015

On 7/14/2015 10:41 PM, Jaroslav Hajtmar wrote:
> Hello ConTeXist.
> I hope that my crazy questions not much bother.
> This time I needed to get to the fair value of the parameter, delivering
> to lua function over the content macros.
> Obviously it's my misunderstanding of the functioning of expansion in
> case maker with optional parameters, or you really can not explain the
> functioning of the transmission values. It seems that is passed to a
> sort of reference as to the actual contents of the macro perhaps can not
> even get through Lua. Or did they?
> The following minimal example, perhaps explain what going on.

Tex has tokens so "foo" is three tokens "f" "o" "o" and not a string. 
This means that you need to turn tokens into a string (using the 
(new)token library). It means that you need to be well aware of tex's 
internals and the way it deals with input -> tokenization -> expansion 
etc etc.

> The question ultimately: Is there any alternative how using Lua somehow
> easily evaluate the macro content? For example to determine whether two
> different macros have the same content?

just avoid storing stuff in macros .. .as most you do seem to be lua, 
keep your data in lua. If you put something in a token register you can 
consult it as string but even then it cannot be what you expect as 
embedded macros don't get expanded (for good reason as they can be 


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