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[Henri Lesourd <address@hidden>]

> Thanks for the hint. Unfortunately, my experience with TeXmacs does 
> not suffice to use this information. :-(
>
> My first try so far was
>    <extern|get-name-buffer>
> which gives me "insecure script" or - if I switch off security - "?"
>
> Is there any special trick about it?
It seems that by default, (get-name-buffer) is considered as insecure,
I dont know why. One can, as you did, turn security off to use it in a
macro, but you go in another problem, which is that the type of the result
of (get-name-buffer) is <url>, not <tree>. Consequently, this result is
displayed as a "?" in the document.

How did I found that the type of the result of (get-name-buffer) is <url> ?
I tried "(get-name-buffer)" in a Scheme session :
[[
scheme] (get-name-buffer)
  <url /home/henri/test.tm>  <<<----- the type is <url ...>
scheme] _
]])

You can also use more than only a function name in an <extern>, namely 
Scheme
code contained in a (lambda) instruction. For example :
[[
<extern|(lambda () (+ 2 2))>
]]

gives :
[[
4
]]

Now we can write a macro to do the job :
[[
<assign|the-pathname|<macro|(lambda () (url->string (get-name-buffer)))>>
]]

The macro above uses the (url->string) routine that converts an object 
from the
<url> type to the <string> type. Once converted this way, it's OK.

(To know the name of the available TeXmacs primitives, look in
src/src/Guile/Glue/build-glue-basic(or editor, or server).scm).

But unfortunately, the macro above doesn't work yet, because the symbol ">"
that appears in "url->string" is a special character from the TeXmacs 
point of
view : if you look in the source, the macro is encoded this way :
[[
<assign|the-pathname|<macro|<extern|(lambda () (url-\<gtr\>string  
(get-name-buffer)))>>>
]]

so because of this f*****g encoding, TeXmacs calls the 
"(url-\<gtr\>string)" routine
instead of the real "(url->string)" !

So the final trick is (the macro below should be one-lined in TeXmacs) :

<assign|the-pathname|<macro|<extern|(lambda () ((eval-string
(string-append "url-" (make-string 1 (string-ref "\<gtr\>" 4)) "string"))
(get-name-buffer)))>>>

Then :
[[
<the-pathname>
]]

gives you what you want :-)

Best, Henri

P.S. : The attached .tm file contains the macro and some examples.

P.S(2) : You can find a (work in progress) tutorial which explains in 
detail how
  to write macros, macros in Scheme, and how to package all these things in
  plugins at http://www.ags.uni-sb.de/~henri/texmacs/. 
<http://www.ags.uni-sb.de/%7Ehenri/texmacs/aTeXmacsTutorial.pdf>