Re: [Texmacs-dev] Logical cursor movement

[Joris van der Hoeven]

> > The first type of cursor movement basically only implements
> > 'go-right' and 'go-left' in a satisfactory way.
> > For instance given $a + \frac{b}{c} + d$ and
> > moving to the right behind 'a', yields the successive positions
> > 
> >   $a +| \frac{b}{c} + d$
> >   $a + \frac{|b}{c} + d$
> >   $a + \frac{b|}{c} + d$
> >   $a + \frac{b}{|c} + d$
> >   $a + \frac{b}{c|} + d$
> >   $a + \frac{b}{c}| + d$
> >   $a + \frac{b}{c} +| d$
> >   $a + \frac{b}{c} + d|$
> >   $a + \frac{b}{c} + d$|
> > 
> > Moving up and down strongly depends on the particular kind
> > of markup one is in. For instance, inside normal text,
> > 'go-down' might go to the beginning of the next paragraph.
> 
> Right. How do you plan to make logical and physical cursor movement
> coexist? Perhaps arrows for one and A-arrows for the other?. 

Yes, although I am not yet sure about which modifier keys to use.
Indeed, there are many types of directional actions,
such as inserting arguments, rows or columns, alignment of cells,
or redimensioning sizes of pictures and white space.
We have to find out which ones are used most frequently,
because these will get the C-, A- and M- prefixes.
Others will have to do with A-C-, M-C-, M-A-, etc.
I personally think that logical cursor movement of
the first type will not be used very much.

> > As to the second kind of cursor movement, we first have 'go-right',
> > 'go-left' (and 'go-up' and 'go-down' in matrix-like structures) 
> > which go to the next and previous argument.
> > However, we have some choice here, since we may move
> > to the end or the start of the next argument.
> 
> I am not sure I understand this. What is the start or the end of an
> argument if it's still not filled?

Who said that the argument is necessarily "not yet filled"?
If an argument is empty, then it start and end coincide.

> I'm thinking about the issue (more precisely, trying to remember what
> did I think some months ago). Although my thoughts were mostly about
> *text* environments.

Tables are similar to text environments in this respect.
For instance, in my example, you may replace the list of arguments
in a row by a list of arguments in an inactive macro expansion or
function call.

> One question: the logical cursor movement inside macros would mimic the
> creation order of the arguments?.

Yes; if you have a macro

        \newcommand{\swap}[2]{#2#1}

then "moving to the right" inside the macro would correspond
to moving to the left and vice versa.