We should move this to the thread

What alternative for scantokens( "btex " & texcommands & " etex”)?

I’ve put my vardef there. The calls to this vardef are created by lua code.

I need to fix two things: use a string variable to build a btex-etex construct and be able to use (almost) any character in that variable. 

I can adapt the strings, if I know what I have to replace things with. I can manipulate the strings while still in lua. But if I change it and then via MP hand it to a \type{} statement in ConTeXt the replacement will be typeset literally. So, it will be pretty complex. If I drop the use of \type{} inside the btex-etex I have to ‘escape' everything that TeX doesn’t see as normal text catcode. That, again might play havoc with breaking words across lines later.

G

On 29 Mar 2020, at 15:09, Wolfgang Schuster <wolfgang.schuster.lists@gmail.com> wrote:

Gerben Wierda schrieb am 29.03.2020 um 15:06:
On 29 Mar 2020, at 14:35, Wolfgang Schuster <wolfgang.schuster.lists@gmail.com <mailto:wolfgang.schuster.lists@gmail.com>> wrote:

Gerben Wierda schrieb am 29.03.2020 um 14:30:
On 29 Mar 2020, at 12:58, Wolfgang Schuster <wolfgang.schuster.lists@gmail.com <mailto:wolfgang.schuster.lists@gmail.com>> wrote:

Gerben Wierda schrieb am 29.03.2020 um 12:52:
I am using MetaFun (Lua code) to create METAPOST commands from an XML file. One of the issues I am running into that in METAPOST I have to handle strings with " characters in them and METAPOST doesn’t like those. The argument using the string
Foo "Bar” Foo

    ^^^

Use correct left quotation marks or \quotation{…}.
I’m not hard coding the string, I’m reading it from an XML. So, whatever I do, I need to do it by manipulating the string.
E.g. if the string I read contains
Foo "Bar” Foo
your suggestion means  I have to programmatically change that to
Foo \quotation{Bar} Foo
which is too complicated, given that I don’t have regular expression replace at my disposal.
I might be able to change al “ instances into something else by walking through the string and building a new one.

Your example uses " before Bar and not “ which is the problem.
Yes, I am aware that that is my problem. It is just that I do not have the luxury to decide myself what will be put in the string. It must work for any string. So, I will have to be putting that string to \type and make sure that is used as the label.

Does btex .. etex help or can't you change the strings and replace the quotation marks before you pass them to MetaPost?

\starttext

\startMPcode
draw textext.urt("One");
draw btex "Two" etex shifted (0,15);
label.urt("Three",(0,30));
label.urt(btex "Four" etex,(0,45));
\stopMPcode

\stoptext

Wolfgang