| Newbie questions about Pliant
assignment operator
I have a datatype SV, and I need to execute different
code when I assigned integer into it, or when I assign a string into it, etc. |
| Message posted by reitman on 2003/08/16 16:24:39 |
var SV sv1 sv2
sv1 := 10
sv2 := "10"
should execute the code
lperl_sv_setiv sv1 10
lperl_sv_setpv sv2 "10"
Whats the easiest way to accomplish this ?
Related question. I am continuing work on embedding perl in pliant.
Now I am at the array implementation, which is a proxy to an array in the
perl space. I would like to have the following code to work,
gvar PerlArray a
a:2 := 10
what should happen is, a:2 should return an SV, and I should assign 10 into this SV. The code generated is
var Address ptr_to_sv
var SV sv
ptr_to_sv := lperl_av_fetch a:av 2
sv := ptr_to_sv map SV
lperl_sv_setiv sv 10
I have looked at array.pli, and wrote this,
method a '' i -> sv
arg PerlArray a
arg_C SV sv
var Address ptr
var SV sv_tmp
ptr := lperl_av_fetch a:av i
sv_tmp := ptr map Address # auto-casting from Address to SV
(addressof Pointer:SV sv) map Address := sv_tmp
I get confused over what I am returning in 'sv'. Should I just be
setting sv := sv_tmp for the code to generate what I am expecting ?
Or should I be returning ptr, and the special arg_C will make it act
as a C++ reference ?
Thanks,
Boris
|
| Message posted by hubert.tonneau on 2003/08/16 18:46:29 |
The biggest problem for me is to understand what your 'SV' data type is
intended to code.
> Whats the easiest way to accomplish this ?
Define casting functions from 'Str' and 'Int' to 'SV'
function 'cast SV' i -> sv
arg Int i ; arg SV sv
reduction
lperl_sv_setiv sv i
> I get confused over what I am returning in 'sv'
Think about:
method a '' i -> sv
arg PerlArray a ; arg_C SV sv
as basically the same as:
method a '' i -> sv
arg PerlArray a ; arg Pointer:SV sv
|
| Message posted by reitman on 2003/08/17 02:36:23 |
About SV:
if I was in C, I would do,
typedef Address SV
but in Pliant I did,
type SV
field Address a
since I din't know how to accomplish the typedef in Pliant.
All operations on an SV happen through the C-wrapped API.
like sv := 10 becomes (lperl_setiv sv 10)
|
| Message posted by hubert.tonneau on 2003/08/17 08:42:39 |
> if I was in C, I would do,
> typedef Address SV
In Pliant, just do:
alias SV Address
and it will say that 'SV' is a new name of 'Address'.
Also, my point of view is that using a new name is generaly a bad idea,
because people tend to believe that it's enough to be later abble to change
the new type to something else, but most of the time, it's not. |