mailing-list for TeXmacs Users

[Henri Lesourd <address@hidden>]

Takama M. wrote:

>Hi,
>
>I feel pleasure of using TeXmacs recently.
>Now I want to know the method to get value of the variable
>stored in the TeXmacs environment from scheme side.
>
>I try to find those ...
>and found such procedures "get-env" and "get-env-tree".
>
>Though the help pages of the TeXmacs are very well and
>useful, those procedures are not documented in detail.
>
>The lines below are my poor efforts.
>Am i on the right path?
>  
>
Yes, it's OK.


>Or are there other better methods?
>
>  
>
There is another way, which is to directly
traverse the document tree to find the <assign|...>
or <with|...> constructs, then read the data. But
this way is slower and more syntactic, although
the other one is sometimes buggy due to problems
in the C++. Inside the file graphics-utils.scm,
see the implementation of:

(tm-find-prop p var)
(get-upwards-tree-property p var)

etc.

(read on older messages on the mailing list,
there are some which document how to traverse
TeXmacs documents as tree).


><assign|xx|7>
>scheme] (get-env "xx")
>=> "7"
>OK!
>
><assign|tpl|<tuple|H|e|l|lo>>
>scheme] (get-env "tpl")
>=> ""
>???
>
>  
>
It's because the output of (get-env) is supposed
to be a string, thus when the value is a non
atomic tree, it spits you out BS.


>scheme] (get-env-tree "tpl")
>=> <tuple|H|e|l|l|o>
>Hummm...
>
>  
>
In fact, using (get-env-tree) all the time
is simpler, then you convert the trees to
s-expressions by means of (tree->stree),
and you always deal with Scheme objects.

(isn't very optimal if the values are
big, though...).


>scheme] (tm-car (get-env-tree "tpl"))
>=> tuple
>  
>
This one is cool.


>scheme] (tm-cdr (get-env-tree "tpl"))
>=> (<tree H> <tree e> <tree l> <tree l> <tree o>)
>
>  
>
That one is shitty, for you can't avoid
rewriting the tree, then.

Much better to use:
(tree-label $TREE) -> Symbol
(tree-arity $TREE) -> Integer
(tree-ref $TREE $INDEX) -> Tree

to read/traverse the tree.


>scheme] (define (tmcadr t) (tm-car (tm-cdr t)))
>scheme] (tmcadr (get-env-tree "tpl"))
>=> H
>
>  
>
tree-ref $TREE 0 = tmcadr, but constant-time,
without the consings.