Le 02/06/2011 12:25, Christophe Jorssen a écrit :
2011/6/2 Paul Isambert<[email protected]>:

I wanted to try some hack with token.create/token.expand, but I found that:

\def\A{1}
\directlua{
  local A = token.create("A")
  token.expand(A)
}

produces an "Undefined control sequence" error. Which is all the more
surprising as if the token is fed to TeX in the token_filter callback, as in
the stupid example below, the control sequence is fine:

\def\A{1}
\directlua{
callback.register("token_filter",
  function ()
    callback.register("token_filter", nil)
    return token.create("A")
  end)
}

Have I misunderstood something or should I pay a visit to the bug tracker?
I did exactly the same thing (well, the first part, I don't understand
the second with the callback yet...) and got the same error but I felt
ashamed of posting it here thinking I may have missed something
trivial. So thank you Paul :-)

You're welcome. But nobody should refrain from posting here, even simple questions (which aren't necessarily so trivial as they seem) can be answered.

By the way, I would highly appreciate some basic usage examples ot the
token_filter callback and the token library.

If you're a TUG member, you can have a look at my paper in the last TUGboat: https://www.tug.org/members/TUGboat/tb32-1/tb100isambert.pdf. Note that the example of use is pretty stupid, you can do things much more easily with tex.print (something I realized only later in a post by Ulrike on this list).

Anyway, I'll try to write something in the wiki, although I don't have any convincing example of use (I haven't investigated the matter much).

Best,
Paul

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