Re: [Pika-dev] alists, list issues

[Tom Lord]

    > From: Andreas Rottmann <address@hidden>

    > I just found out that there are more issues in my list code, except
    > for SCM_LSET: I sometimes set the result storage and later referenced
    > one of the parameters. This is of course wrong, since it means
    > scm_func (x, arena, x) won't reliably work. I'll fix those along with
    > the LSET issue. 

Oh good.   I'd started reviewing and fixing things like that but I'll
hold off till your done.

Right: 

~ return parameters are permitted to be the same as input
  parameters.

~ never dereference a `t_scm_word *' return or input parameter as
  either lvalue or rvalue.

~ never reference a local `t_scm_word' variable except with a & in 
  front of it (never use its value, only its address).

  So, not `*result = l.tail'  but `SCM_LSET (result, &l.tail)'

~ always use scm_values_eq, not == or !=

  So, not `if (l.fast == l.slow)' but 
  `if (scm_values_eq (arena, &l.fast, &l.slow))'

~ generally speaking, don't include system headers directly

  So, not `#include <stdarg.h>' but `#include "hackerlab/os/stdarg.h"'


The other thing I've found is non-critical coding issues (i.e.,
perfection about this kind of thing is not critical):

~ use parentheses, not precedence

  Not `if (tail && n > 0)' but `if (tail && (n > 0))'




    > Meanwhile, I've started implementing some alist functions, reaping the
    > code from systas and unfinished-code. Again, I've an API question;
    > scm_acons and scm_ass{q,v,oc} are clear to me, but should the C names
    > for ass{q,v,oc}-ref and del{q,v,ete} (not really alist function, but
    > needed by alist code) be? 

Just what you'd think:

     scm_ass{q,v,oc}_ref

     scm_del{q,v,ete}


-t