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[Henri Lesourd <address@hidden>]

Takama M. wrote:

> Henri Lesourd  wrote:
>
> > Much better to use:
> > (tree-label $TREE) -> Symbol
> > (tree-arity $TREE) -> Integer
> > (tree-ref $TREE $INDEX) -> Tree
> >
> > to read/traverse the tree.
> Thanks for your kind response.
> It's helpful for me.
> I asked the previous question because
> i consider some coordinate transformation
> procedure for my graphics drawing which
> refer to the value of variables such as
> "gr-geometry" and "gr-grid".
Then precisely, you should use the
functions above, for there is a problem
with the (get-env-X) functions: they
depend on the *current cursor position*,
which raises unsolveable problems if
you try to use those in other contexts
than an interactively editing the object
you are currently calculating on.

That's why even in the vector graphics
editor I wrote 2 years ago, I came to
use exclusively functions built on top
of the API above, otherwise, being forced
to think all the time at : "am I 100% sure
the cursor is appropriately positioned",
it's often too much messy, except if
you don't care writing code which can
be broken in some baroque ways.