[Lib2geom-devel] some todos and wishes

[<Jea...@ma...>]

Hi!

After playing a bit with the library, I came up with some todos and
wishes, that I submit before I forget them; some might already be there
but I was not aware, or some might be bad ideas for some other reason...
These are just suggestions:

First, things would be more pleasant if we had:
- automatic conversions: sb to pw<sb> (Linear to sb, double to Linear).
- allow +,-,* between double,sb,pw<sb>,d2<pw<sb>>,d2<pw<sb>>.
- allow composition sb(pw<sb>)
- allow composition d2<pw<sb>>(sb) and pw<d2<sb>>(sb)
- define a plotter function for d2<pw<sb>> and pw<d2<sb>> (for toys/tests)

I noticed some function are out of age (this is my fault!!)
- update 'unit-vector'
- update 'arc-length-sb'

Some remarks about our conventions:
- define "bridges" between d2<pw<sb>> and pw<d2<sb>>.
  Although d2<pw<sb>> is usefull in some situations (plotting a function
  for instance), many operations require synchronous cuts, so pw<d2<sb>>
  instead. Note that once a d2<pw<sb>> has synchronous cuts, there is no
  synchronizing for each new operation... To make this implicit, our
  functions should accept both d2<pw<sb>> and pw<d2<sb>>, and do some
  conversion if needed. Or should we get rid of d2<pw<sb>>?
- fix convention about empty sb/pw<sb>: an empty sb is the constant 0
  while empty pw<sb> are not allowed. How do we represent 0 in pw<sb>
  world? as (pw<sb>)Linear(0)?

Some less relevant todos:
- define some standard functions for pw<sb>: sqrt, cos, sin...
- define pw<sb> and d2<pw<sb>> bounds.

What do you think?
JF.