Tassilo von Parseval wrote:
On Fri, Oct 31, 2003 at 12:39:14PM +1100 Sisyphus wrote:
Steve Hay wrote:
So I tried rewriting my original example like this:
SV *
hello()
PREINIT:
char*chartext;
SV*svtext;
CODE:
Newz(0, chartext, 13, char);
strcpy(chartext,
On Fri, Oct 31, 2003 at 09:34:46AM + Steve Hay wrote:
Tassilo von Parseval wrote:
I get a segfault, which is what I would expect. You only allocate memory
for the string but not for the SV to be returned.
[snip]
One could change it to:
SV *
hello()
PREINIT:
Steve Hay [EMAIL PROTECTED] writes:
I understand the second case there -- when the xsub is called as
hello(1) -- but that leaves me wondering what ST(0) was in the case
where the xsub was called without arguments.
It is a stack - a hunk of memory.
So if you don't have any args one it is:
-
Steve Hay wrote:
At this point I have:
void
hello(...)
PREINIT:
char*chartext;
CODE:
Newz(0, chartext, 13, char);
strcpy(chartext, Hello, world);
ST(0) = newSV(0);
sv_usepvn(ST(0), chartext, 13);
By the way what is the reason you do a PREINIT which does no init rather
than
CODE:
{
char *chartext;
...
}
?
I once fell foul of the problem described in the PREINIT entry in the
perlxs manpage, namely: If a variable is declared inside a CODE:
section it will follow any typemap code
Steve Hay [EMAIL PROTECTED] writes:
What's the best way to have an XSUB return a string (char *) when the
caller doesn't know how big that string will be?
At a mortal string SV:
void
my_xsub()
CODE:
{
ST(0) = sv_2mortal(newSVpv(string,strlen(string));
XSRETURN(1);
}
I like that style
Nick Ing-Simmons wrote:
SV *
my_xsub()
CODE:
{
RETVAL = sv_2mortal(newSVpv(string,strlen(string));
}
OUTPUT:
RETVAL
As regards that, Nick - is the 'sv_2mortal' part necessary ?
I thought *not* - but I'm sometimes wrong :-)
Cheers,
Rob
--
Any emails containing attachments will be deleted from
On Thu, Oct 30, 2003 at 08:21:38AM + Nick Ing-Simmons wrote:
Steve Hay [EMAIL PROTECTED] writes:
What's the best way to have an XSUB return a string (char *) when the
caller doesn't know how big that string will be?
At a mortal string SV:
void
my_xsub()
CODE:
{
ST(0) =
Tassilo von Parseval wrote:
On Thu, Oct 30, 2003 at 08:02:53PM +1100 Sisyphus wrote:
Nick Ing-Simmons wrote:
SV *
my_xsub()
CODE:
{
RETVAL = sv_2mortal(newSVpv(string,strlen(string));
}
OUTPUT:
RETVAL
As regards that, Nick - is the 'sv_2mortal' part necessary ?
I thought *not* - but I'm
Tassilo Parseval [EMAIL PROTECTED] writes:
Is this certain that my_xsub() returns a mortal?
No - but it needs to return something which something will eventually free.
When looking into the
generated C code, I see:
{
char *RETVAL;
RETVAL = string;
sv_setpv(TARG, RETVAL);
Sisyphus [EMAIL PROTECTED] writes:
Tassilo von Parseval wrote:
On Thu, Oct 30, 2003 at 08:02:53PM +1100 Sisyphus wrote:
Nick Ing-Simmons wrote:
SV *
my_xsub()
CODE:
{
RETVAL = sv_2mortal(newSVpv(string,strlen(string));
}
OUTPUT:
RETVAL
As regards that, Nick - is the 'sv_2mortal' part
On Thu, Oct 30, 2003 at 11:13:47AM + Nick Ing-Simmons wrote:
Sisyphus [EMAIL PROTECTED] writes:
Tassilo von Parseval wrote:
It is. If you have code like
{
my $var = my_xsub();
...
}
and want $var to be cleaned up when it falls out of scope, you
Tassilo Parseval [EMAIL PROTECTED] writes:
On Thu, Oct 30, 2003 at 11:13:47AM + Nick Ing-Simmons wrote:
Sisyphus [EMAIL PROTECTED] writes:
Tassilo von Parseval wrote:
It is. If you have code like
{
my $var = my_xsub();
...
}
Mortals are just
Nick Ing-Simmons wrote:
The sv_2mortal _IS_ needed in the
void
my_xsub()
CODE:
{
ST(0) = sv_2mortal(newSVpv(string,strlen(string));
XSRETURN(1);
}
case.
But it is inserted for you SV * return case:
{
RETVAL=newSV...;
}
#line 25 Foo.c
ST(0) = RETVAL;
sv_2mortal(ST(0));
}
Sisyphus [EMAIL PROTECTED] writes:
Nick Ing-Simmons wrote:
The sv_2mortal _IS_ needed in the
void
my_xsub()
CODE:
{
ST(0) = sv_2mortal(newSVpv(string,strlen(string));
XSRETURN(1);
}
case.
But it is inserted for you SV * return case:
{
RETVAL=newSV...;
}
#line 25 Foo.c
ST(0) =
On Thu, 2003-10-30 at 16:14, Steve Hay wrote:
SV *
hello()
PREINIT:
char*chartext;
SV*svtext;
CODE:
Newz(0, chartext, 13, char);
strcpy(chartext, Hello, world);
sv_usepvn(svtext, chartext, 13);
RETVAL = svtext;
Steve Hay wrote:
So I tried rewriting my original example like this:
SV *
hello()
PREINIT:
char*chartext;
SV*svtext;
CODE:
Newz(0, chartext, 13, char);
strcpy(chartext, Hello, world);
sv_usepvn(svtext, chartext, 13);
RETVAL = svtext;
What's the best way to have an XSUB return a string (char *) when the
caller doesn't know how big that string will be?
In C a function can't return a pointer to a function-static variable,
but in Perl you can get away with a function returning a reference to a
function-scoped lexical variable.
Steve Hay wrote:
What's the best way to have an XSUB return a string (char *) when the
caller doesn't know how big that string will be?
In C a function can't return a pointer to a function-static variable,
but in Perl you can get away with a function returning a reference to a
function-scoped
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