explain please

explain please

[Hans van der Meer]

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How can the crash in the minimal example here be explained? And is there a solution to avoid this and make the crash going away "without having to jump through special hoops"?

dr. Hans van der Meer


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% Interface to Lua call:
\startluacode
-- Define namespace as test
test = test or {}
test.luafunc = function (argument)
	return "RETURN: " .. argument
end
test.Upper = function(s)
	return s and string.upper(s) or ""
end
\stopluacode
\def\LuaFunc#1{\directlua{tex.print(test.luafunc("#1"))}}
\def\ChangeUpper#1{\directlua{tex.print(test.Upper("#1"))}}
\starttext
{\bf Lua and interface code:}
\starttyping
\startluacode
-- Define namespace as test
test = test or {}
test.luafunc = function (argument)
	return "RETURN: " .. argument
end
test.Upper = function(s)
	return s and string.upper(s) or ""
end
\stopluacode
\def\LuaFunc#1{\directlua{tex.print(test.luafunc("#1"))}}
\def\ChangeUpper#1{\directlua{tex.print(test.Upper("#1"))}}
\def\textex{textex}
\stoptyping
Test of various macros as input argument to Lua functions.\blank
contextversion = \contextversion\blank
\def\textex{textex}

This call didnt crash:
\type{\LuaFunc{\textex}} = \LuaFunc{\textex}\blank

This call didnt crash:
\type{\ChangeUpper{\textex}} = \ChangeUpper{\textex}\blank

This call didnt crash:
\type{\LuaFunc{\ChangeUpper{\textex}}} = \LuaFunc{\ChangeUpper{\textex}}\blank

\type{\currentdate} = \currentdate\crlf
This call didnt crash:
\type{\WORD{\currentdate}} = \WORD{\currentdate}\blank

This call crashed: \type{\LuaFunc{\currentdate}} =\crlf
%\LuaFunc{\currentdate}

This call too: \type{\expanded{\LuaFunc{\currentdate}}} =
%\expanded{\LuaFunc{\currentdate}}
\starttyping
lua error       > lua error on line 54 in file ./currentdate.tex:
token call, syntax: [ctxlua]:1: invalid escape sequence near '"\c'
\stoptyping

Why is "\currentdate" not transferred to the Lua end, even if \type{\expanded} is applied?
\stoptext


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Re: explain please

[Hans Hagen]

On 6/24/2020 9:00 PM, Hans van der Meer wrote:
> How can the crash in the minimal example here be explained? And is there 
> a solution to avoid this and make the crash going away "without having 
> to jump through special hoops"?
because \currentdate is a macro thatv does some magic ... it's nor fully 
expandable

so, lua sees \currentdate == \c as first escaped character coming in and 
that's invalid (\\currentdate would work)

just try

print("\come on") in pure lua

Hans


-----------------------------------------------------------------
                                           Hans Hagen | PRAGMA ADE
               Ridderstraat 27 | 8061 GH Hasselt | The Netherlands
        tel: 038 477 53 69 | www.pragma-ade.nl | www.pragma-pod.nl
-----------------------------------------------------------------
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Re: explain please

[Hans van der Meer]

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\\currentdate 
Neat solution, worked without a hitch. Now I have to remember this for future use ...

dr. Hans van der Meer


> On 24 Jun 2020, at 21:10, Hans Hagen <j.hagen@xs4all.nl> wrote:
> 
> On 6/24/2020 9:00 PM, Hans van der Meer wrote:
>> How can the crash in the minimal example here be explained? And is there a solution to avoid this and make the crash going away "without having to jump through special hoops"?
> because \currentdate is a macro thatv does some magic ... it's nor fully expandable
> 
> so, lua sees \currentdate == \c as first escaped character coming in and that's invalid (\\currentdate would work)
> 
> just try
> 
> print("\come on") in pure lua
> 
> Hans
> 
> 
> -----------------------------------------------------------------
>                                          Hans Hagen | PRAGMA ADE
>              Ridderstraat 27 | 8061 GH Hasselt | The Netherlands
>       tel: 038 477 53 69 | www.pragma-ade.nl | www.pragma-pod.nl
> -----------------------------------------------------------------


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