[GiNaC-devel] remove_dirac_ONE() and documentation patches

[Alexey Sheplyakov]

Hi,


>   Thus I re-write remove_dirac_ONE() without exceptions. The signature
>   of the method has to change, but a user may not notice this in the
>   first approximation. 

There a few fatal differences (which are indeed not so easy to spot):

- A user code might be relying on remove_dirac_ONE() to throw an exception when something goes wrong.
  The patch breaks such a code without a slightest warning from the compiler. 

- Before the patch this:

  remove_dirac_ONE(e, 0, 0);

  used to compile and work just fine. With the patch it also compiles (without a slightest warning),
  and segfaults at the run time (for the last 0 is `bool *success` now).0


>  *  @param e Expression to be processed
> - *  @param rl Value of representation label 
> - *  @param options Defines some internal use */
> -ex remove_dirac_ONE(const ex & e, unsigned char rl = 0, unsigned options = 0);
> + *  @param rl Value of representation label, all dirac_ONE with this or greater value will be processed
> + *  @param success It is changed to false if there is at least one clifford_unit() in the expression
> + *  @param options Defines some internal value for recursive calls, shall be ommited in user code */
> +ex remove_dirac_ONE(const ex & e, unsigned char rl = 0, bool *success = new bool, unsigned options = 0);

Also there's a memory leak (since nobody is going to release that `new bool`).

Therefore I think the patch is wrong and should not be applied.

Possible solutions:

1) 

a) Make a new (overload of) remove_dirac_ONE function:

    ex remove_dirac_ONE(const ex& e, bool& success, unsigned char rl = 0, unsigned options = 0);

   which reports errors without exceptions

b) Don't change the behavior of the existing `ex remove_dirac_ONE(const ex& e, unsigned char rl =0, unsigned options = 0);

2) Leave current `remove_dirac_ONE` as is. It's not broken, there's nothing to fix.

>  The exceptions in remove_dirac_ONE() terminated a Qt Windows application

And fix that application instead (perhaps I could help if the sources and instructions how to reproduce the problem are available)

Best regards,
       Alexey