[Texmacs-dev] Path computations

[Philippe Audebaud]

Hi,

Assume  (for a reason  or another)  one wants  to allow  a script  or program
external to TeXmacs making computations on paths for a document.

here is my experiment (the document is attached to this mail):

----------------------------------><8---------------------------------------
this is a string

<verbatim|(0 13)> is the path, cursor left to the second 'i' letter.

- the meaning is 0=first paragraph in the document, 13=position in the string

<strong|this is a string>

<verbatim|(3 1 13)> for the same postion, and the structure is
<verbatim|\<less\>strong\|this is a string\<gtr\>>

- the meaning is 3=fourth paragraph, 1=second position in the macro, 13=...

<with|mode|math|this is a string>

<verbatim|(6 2 13)> for the same position, the structure being
<verbatim|\<less\>with\|mode\|math\|this is a string\<gtr\>>

- the meaning is 6=sixth para, 2=fourth position in the macro, 13=...
----------------------------------><8---------------------------------------

So what  ? 'strong' is a user  macro, defined in some  TeXmacs package, while
'with' is a  TeXmacs *primitive*. In the first case,  the macro name position
is taken  into account in  the computation. In  the second case, it  is *not*
taken into account.

1) what are  the very reasons for such  a difference within the  two kinds of
'macros' ?

2) If such a behavior must be  preserved, then I think a scheme function like
'primitive?', 'tm-primitive?' (...which ever  the name), returning the status
for these names will be welcome to help developers.

I feel really bad with such a distinction, and TeXmacs crashed badly for many
times  until I  figured out  that  the problem  was *that*  one. Moreover,  I
remember defining a macro with name  'group' without knowing it was a TeXmacs
primitive.  Of  course, several  documents  of  mime  behaved badly  in  this
context! But  no warning  was given  for redefining a  primitive... And  as a
matter of consequence, path computation  changed !  I can also imagine status
changing from  a TeXmacs version  to another, so  the way of  computing paths
seems too much context sensitive to me.

How can we deal best with this issue? 
best,
-- 
Philippe Audebaud.

paths.tm
Description: Path computations