GiNaC with GUI

[Stefan Weinzierl]

Hi,


On Fri, 19 Jan 2001, Richard B. Kreckel wrote:

> Okay, installing all those supporting packages is a somewhat intrusive
> procedure.  We had a close look at it, though.  I have a couple of
> comments on the patches you applied to the GiNaC files.  For those who
> haven't seen them yet, let me sum up: they consist of a bunch of `#ifdef
> __WITH_GUI__' delimited statements that turn the output function to 
> something useful for TeXmacs.  This works great.  But, frankly, it is
> ugly.
> 

Well, I agree that I will not win a beauty contest for programming style
with these patches. 



> Our Todo-List <http://www.ginac.de/ToDo.html> says something about 
> "systematic I/O-Philosophy".  There might be people who wish to have their
> expressions directly print OpenMATH or MathML or MathML or Maple-Input or 
> Mathematica-Input... You name it.  What we *should* do instead of defining
> more and more .print_my_fancy_format(ostream & os) methods to the
> interfaces is this:
> 
> * define some printflags (maybe an enum) that tells how the output should
>   look like,
> 
> * make ex::print(), basic::print()... aware of these flags and handle
>   everything inside those print functions -- but without bloating them
>   (by moving out code into static functions as far as reasonable).
> 
> * [optional] some of the already existent print methods may be 
>   eliminated now, if the flags can incorporate this distinction.
> 
> Let's go one step further towards "the best of all worlds"(tm).  Ideally,
> in the end one would write code like this, using manipuators:
> 
>     ex e = 3/2*pow(Pi,2);
>     cout << e << endl;                // prints 3/2*Pi^2;
>     cout << ginsh << e << endl;       // ...the same in this case...
>     cout << tex << e << endl;         // prints \frac{3}{2}\Pi^2
>                                       //         1    2
>     cout << pretty << e << endl;      // prints --- Pi
>     // ... imagine more...            //         2
> 
> This can't be done so simply, since std::cout is an object of type ostream
> and it simply not clever enough to remember such states as tex, pretty and
> so on.  It is only designed for hex, oct, boolalpha and a few others.
> However, it is straightforward to derive your own class from ostream that
> handles such flags and define a GiNaC::ostream cout; somewhere so one
> could choose it simply by saying using GiNaC::cout;.  Chapter 21 in Bjarne
> Stroustrup's Book TC++PL3 (The C++ Programming Language, 3rd ed.) is a
> readable and rather realistic description of streams in C++ and gives
> enough insight to implement this.
> 
> Stefan, since you had a look at the output and understand it and since the
> output must be reorganized anyways and since I am rather busy on other
> frontiers and since I would love to have your routines in GiNaC (once they
> are reorganized), would you be willing to volunteer on this?  And
> remember: good patches are very welcome!
> 



I can have a look at it, but expect something more on a time scale
of months than weeks.
The reasons are that at the moment I'm not yet too familiar with the
source code of GiNaC, and secondly, I would like to write some
applications/extensions first.
(You write good code only if a problem really bothers you !)


 Stefan