evaluating math w/o recompile

[Joe English]

zador-anthony at CS.YALE.EDU (anthony zador) writes:
>I would like to be able to specify the form of the function f
>at *run time* (no recompiles). That is, i would like 
>to place a line of math
>in some file and have the program read it in and evaluate it.

How about writing a set of math interface 
functions that take, instead of a fixed set of parameters,
an argv/argc pair?  I'm doing something like that right
now in a report generator I'm writing:

enum valuetype {  vInt, vFloat, vString ... };

typedef struct {
   enum valuetype tag;
   union {
      int ival;
      double fval;
      char *sval;
      ...
   } datum;
} value;


Then for the interface function:

value somefunc(int argc,value *argv)

{
    /* use argc parameters from the argv array.  Type-checking
       of arguments is done by the parser & function
       lookup table.
    */
}

If you don't need full generality, you can use
'double *argv'.


--Joe English

  jeenglis at nunki.usc.edu