struct variable definition (in var.h)

[John Darrington]

So I'm onto the EXAMINE command, which means that I'm going to have to
look again at percentiles and calculation of ranks.  Much of this was
done before in the FREQUENCIES command.  However it needs to be
abstracted somewhat if it's going to be reuseable.

Currently I'm not too impressed with the system we've been using for
storing per procedure info which has a rather cumbersome general
purpose storage area in the definition of the variable type:

struct variable
  {

  .
  .
  .

    /* Per-procedure info. */
    void *aux;
    struct get_proc get;
    union
      {
        struct crosstab_proc crs;
        struct frequencies_proc frq;
        struct list_proc lst;
        struct means_proc mns;
        struct matrix_data_proc mxd;
        struct match_files_proc mtf;
        struct group_proc grp_data;
      }
    p;
};


I think there's a lot of problems with this approach.  To name some:

1. Doesn't promote reuse between procedures.
2. Makes no provision for factored variables.
3. There'll end up being a lot of members to that union
4. Makes var.h dependent upon almost every procedure definition.

Does anyone object if I rework it?

J'

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