ficl-developers

[Ficl-developers] poping values off the vm stack?

[Michel P. <mi...@zo...>]

I never saw my last message come to the list, so for anyone who was
thinking of answering it don't bother, I figured out my problem.  If you
didn't see it than don't worry about it.

The current fun little thing I"m working on is embedding ficl in
Python.  I have it working pretty well at the moment, I can create vms
and evalute python strings containing forth code, and I can also push
integers onto the stack from python, but I can't figure out how to pop
them.  That's my question.  I have these two C functions:

static PyObject *
FiclVM_pushint(FiclVMObject *self, PyObject *args)
{
  int x;
  if (!PyArg_ParseTuple(args, "i:pushInt", &x))
    return NULL;
  vmPush(self->ficl_vm, LVALUEtoCELL(x));
  Py_INCREF(Py_None);
  return Py_None;
}


static PyObject *
FiclVM_popint(FiclVMObject *self, PyObject *args)
{
  CELL c;
  PyObject *i;
  if (!PyArg_ParseTuple(args, ":pushInt"))
    return NULL;
  c = vmPop(self->ficl_vm);
  i = PyInt_FromLong((long)&c);
  Py_INCREF(i);
  return i;
}

The first function works fine and pushes the right integer onto the
Forth stack.  The second function does return a valid python integer but
when I push '5' I get '-1758473533' or whatever back.  How can I turn
'c' into the right integer value?  PyInt_FromLong expects a long value.

Thanks,

-Michel

Re: [Ficl-developers] poping values off the vm stack?

[Bob D. <bo...@dr...>]

11/29/2001 9:08:51 PM, Michel Pelletier <mi...@zo...> wrote:

>The current fun little thing I"m working on is embedding ficl in
>Python.

How very cool. Will we soon be able to do ficl scripting in Zope?
Can you send me a copy of your stuff when it gets close to working?

> I have it working pretty well at the moment, I can create vms
>and evalute python strings containing forth code, and I can also push
>integers onto the stack from python, but I can't figure out how to pop
>them.  That's my question.  I have these two C functions:

>static PyObject *
>FiclVM_pushint(FiclVMObject *self, PyObject *args)
>{
>  int x;
>  if (!PyArg_ParseTuple(args, "i:pushInt", &x))
>    return NULL;
>  vmPush(self->ficl_vm, LVALUEtoCELL(x));
>  Py_INCREF(Py_None);
>  return Py_None;
>}

The only thing I notice right off the bat is that LVALUEtoCELL expects at least a long, 
and you're handing it an int. This will of course only work if int and long are the same 
length on  your platform. Wouldn't declaring x a long make this clearer? Perhaps using 
unambiguous types such as int32_t, or more directly-relevent types such as FICL_INT, 
would be better?

>static PyObject *
>FiclVM_popint(FiclVMObject *self, PyObject *args)
>{
>  CELL c;
>  PyObject *i;
>  if (!PyArg_ParseTuple(args, ":pushInt"))
>    return NULL;
>  c = vmPop(self->ficl_vm);
>  i = PyInt_FromLong((long)&c);
>  Py_INCREF(i);
>  return i;
>}

I don't think that you want to take the address of c here :-)

Quoting http://www.python.org/doc/current/api/intObjects.html

: PyObject* PyInt_FromLong(long ival) 
: Return value: New reference. 
: Creates a new integer object with a value of ival. 

Perhaps you meant &c->i ? In any event, unless sizeof(long) = sizeof(float) =
sizeof(void *) = sizeof(void (*)(void)) on your platform, beware of alignment
issues if you just use the cell union without a member reference.

Also, if the int type is already a long on your system, I'd personally rather see just

  i = PyInt_FromLong(c.i);

But now I'm probably just being picky.

>The first function works fine and pushes the right integer onto the
>Forth stack.  The second function does return a valid python integer but
>when I push '5' I get '-1758473533' or whatever back.

Yes, addresses can be quite large numbers... :-)

> How can I turn
>'c' into the right integer value?  PyInt_FromLong expects a long value.

Feed it the value rather than the address? :-)

>Thanks,

No problem.

>-Michel
>
>_______________________________________________
>Ficl-developers mailing list
>Fic...@li...
>https://lists.sourceforge.net/lists/listinfo/ficl-developers
>
>

Re: [Ficl-developers] poping values off the vm stack?

[Michel P. <mi...@zo...>]

Bob Drzyzgula wrote:
> 
> 11/29/2001 9:08:51 PM, Michel Pelletier <mi...@zo...> wrote:
> 
> >The current fun little thing I"m working on is embedding ficl in
> >Python.
> 
> How very cool. Will we soon be able to do ficl scripting in Zope?

Yep, actually that works right now if you wanted to use it from External
Methods or a Zope python product and all you cared about was passing
integers into and out of forth.  See my other email about working on
getting other Python types in and out.

This is awesome, Python is my favorite language and Forth was my first! 
Seeing the two of them together is strangely pleasing. ;)

> Can you send me a copy of your stuff when it gets close to working?

Uhm.. let me work on the packaging a bit more and I'll get it to you.

> The only thing I notice right off the bat is that LVALUEtoCELL expects at least a long,
> and you're handing it an int. This will of course only work if int and long are the same
> length on  your platform. Wouldn't declaring x a long make this clearer? 

Sounds good to me.  Works too.

> Also, if the int type is already a long on your system, I'd personally rather see just
> 
>   i = PyInt_FromLong(c.i);
> 
> But now I'm probably just being picky.

john sadler suggested that to me earlier and it works great.  I'll
probably spend a few more hours on this tommorow and checked into a CVS
that others can have access too if you think you want to help add Ficl
to Python. ;)

-Michel

Re: [Ficl-developers] poping values off the vm stack?

[Bob D. <bo...@dr...>]

11/29/2001 11:03:30 PM, Michel Pelletier <mi...@zo...> wrote:

>This is awesome, Python is my favorite language and Forth was my first! 
>Seeing the two of them together is strangely pleasing. ;)

That's about how I feel about it, although I think that my first language was APL. Not that 
this means I'd like to see APL embedded in Python. Ficl embedded in APL OTOH -- that
would certainly make one's head spin. :-)

>john sadler suggested that to me earlier and it works great.  I'll
>probably spend a few more hours on this tommorow and checked into a CVS
>that others can have access too if you think you want to help add Ficl
>to Python. ;)

Let me know. You're right -- this is a strangely appealing project. Such coolness should 
be rewarded -- maybe I should buy your book instead of just using the PDF, I sprung for 
the two Beehive books :-)

--Bob