Re: [Tinycc-devel] Tinycc issues

[Dominic Mazzoni]

Neil Bradley wrote:
> > 2. Forward-declare arrays:
> >   With gcc, I am allowed to forward-declare an array of unspecified size,
> >   and then actually specify the size (implicitly) later in the code.  For
> >   example:
> >     int g_primes[];
> >     ...
> >     int g_primes[] = {2, 3, 5, 7, 11, 13, 17, 23};
>
> Why would one do this?

Simple example: I want to define the array in a header file, but 
initialize it in a C file.  I don't want to prespecify the number of 
elements in the array because it's something that changes often, and I 
want to be able to change it without recompiling any other C files.

Actual example: here's something closer to the code I was actually dealing 
with - simplified for this example, of course, but note that g_functions 
is referenced by one of the functions that appears in its own declaration. 
 Ideally I'd like to be able to add a new function to my list without 
having to remember to add one to a constant NUM_FUNCTIONS or something 
like that.

- Dominic


typedef struct {
  char      *name;
  eval_fn_t  eval_f;
} function_t;

function_t g_functions[];

float sin_eval(float x, char *unused)
{
  return sin(x);
}

float cos_eval(float x, char *unused)
{
  return cos(x);
}

float negate_eval(float x, char *fn)
{
  int i;
  while(g_functions[i].name)
    if (!strcmp(g_functions[i].name, fn))
      return -(*g_functions[i].eval_f)(x);
  return NAN;
}

function_t g_functions[] = {
   {"sin", sin_eval},
   {"cos", cos_eval},
   {"negate", negate_eval},
   {NULL, NULL}
};



> -->Neil
>
> ------------------------------------------------------------------------------- 
>
> Neil Bradley             "I've got a fever and the only prescription is 
> MORE
> Synthcom Systems, Inc.    COWBELL!!!"
>
>
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