Native Interoperability

[Tiaansu]

I am wondering if native interoperability is possible for this kind of native(s)?

native MyNative(id, output[], size = sizeof output, ...);
native MyNativeImpl(id, AmxString:output, size, ...) = MyNative;

stock String:MyNativeStr(Template:id, ...)
{    
    new String:output = str_new_buf(8192);
    MyNativeImpl(id, output, 8192, ...); // I know this is invalid
    return output;
}

[IS4Code]

Yes, that is already possible, see the wiki. The tag is AmxStringBuffer: in that case. However note that since v1.4.2, both tags should behave more or less the same, so the code you should actually be valid.

[Tiaansu]

Hello, an update to this. I just read this part:

Unfortunately, printf cannot be modified in such a way, because it doesn't use the standard AMX API to access its parameters. For variadic functions (with ...), the conversion to AmxString is not done automatically and must be done manually.

and it answered my question. I am asking about the variadic arguments.

[IS4Code]

Then see the example below that paragraph, about CallLocalFunction. It works too, but you need to call str_buf_addr manually.

Do you have any particular code or native function you are trying to adapt? I am not aware of any variadic functions that would use output buffers.

[Tiaansu]

Hi, I don't think that using str_buf_addr will work on my case.

As per native function, I want to use it on pawn-templates by Southclaws. (I made my own, but it's not on the github yet, uses the latest samp-rs, just linked Southclaws' plugin for example :))

[IS4Code]

Why? Have you tried it?

[Tiaansu]

Yes. It works like for this:

native MyNative(id, output[], size = sizeof output, ...);
native MyNativeImpl(id, AmxString:output, size, ...) = MyNative;

but in my case (returning PawnPlus string) it won't work (or is there a way to do this?):

native MyNative(id, output[], size = sizeof output, ...);
native MyNativeImpl(id, AmxString:output, size, ...) = MyNative;

stock String:MyNativeStr(Template:id, ...) // <-- this
{    
    new String:output = str_new_buf(8192);
    MyNativeImpl(id, output, 8192, ...);
    return output;
}

[IS4Code]

That one should work in theory (just prefer AmxStringBuffer instead of AmxString). If not (please share how exactly it does not work), it might be an issue with pawn-templates. I know there is (was?) a deficiency in samp-rs that made returning these problematic.

[Tiaansu]

Hi, the deficieny in samp-rs is now gone and this line of code below is working fine:

#include <open.mp>
#include <PawnPlus>
#include <templates>

main()
{
    new Template:templateBanned = CreateTemplate(
        "Your account {{ name }} has been banned!\n\n\
        Reason: {{ reason }}\n\
        Duration: {{ days }} days\n\
        If you disagree, please file an appeal at: {{ forum }}");

    new String:dest = str_new_buf(1024);
    RenderTemplateStr(templateBanned, dest, 1024,
        PAIR_STR("name", "playerName"),
        PAIR_STR("reason", "Hello World"),
        PAIR_INT("days", 30),
        PAIR_STR("forum", "https://forum.website.com")
    );
    str_resize(dest, str_findc(dest, '\0'));
    print_s(dest);
}

what I mean is not working is this:

native RenderTemplateImpl(Template:id, AmxStringBuffer:dest, len, ...) = RenderTemplate;
stock String:RenderTemplateStr(Template:id, ...)
{
    new String:dest = str_new_buf(1024);
    RenderTemplateImpl(id, dest, 1024, ...); // this will throw a compilation error
    str_resize(dest, str_findc(dest, '\0'));

    return dest;
}

Link to my pawn-templates repo: https://github.com/Tiaansu/pawn-templates

[IS4Code]

Don't confuse me like that. 😄 I thought the ... was meant to be a placeholder. Of course you can't use it like that, that is a limitation of Pawn.

There are a few options ‒ use #emit to call it manually or y_va for nicer syntax. PawnPlus also offers a solution ‒ list_get_args("+"), list_new_args in combination with a macro, and pawn_call_native to call the native with the l specifier. This however won't work if the argument is supposed to be a reference.

[Tiaansu]

Hi! I made it using the combination of y_va and #emit 😄

Don't know if the #emit part is safe since I just copied it from other functions that uses it.

stock ReturnTemplate(Template:id, ...)
{    
    static buffer[MAX_TEMPLATE_LENGTH];
    #if defined _INC_y_va
        RenderTemplate(id, buffer, sizeof buffer, ___(1));
        return buffer;
    #else
        const static_args = 1;
        const args_diff = (3 - static_args) * 4;
        
        static args;
        args = numargs();

        if (args > static_args)
        {
            while (--args >= static_args)
            {
                #emit LCTRL     5
                #emit LOAD.alt  args
                #emit SHL.C.alt 2
                #emit ADD.C     12
                #emit ADD
                #emit LOAD.I
                #emit PUSH.pri
            }
            
            #emit PUSH.C        256
            #emit PUSH.C        buffer
            #emit PUSH.S        id
            #emit LOAD.S.pri    8
            #emit ADD.C         args_diff
            #emit PUSH.pri
            #emit SYSREQ.C      RenderTemplate
            #emit LCTRL         5
            #emit SCTRL         4
        }
        else
        {
            RenderTemplate(id, buffer, sizeof buffer);
        }
        return buffer;
    #endif
}

#if defined _PawnPlus_included
stock String:RenderTemplateStr(Template:id, ...)
{
    static buffer[MAX_TEMPLATE_LENGTH];
    #if defined _INC_y_va
        RenderTemplate(id, buffer, sizeof buffer, ___(1));
        return str_new(buffer);
    #else
        const static_args = 1;
        const args_diff = (3 - static_args) * 4;
        
        static args;
        args = numargs();

        if (args > static_args)
        {
            while (--args >= static_args)
            {
                #emit LCTRL     5
                #emit LOAD.alt  args
                #emit SHL.C.alt 2
                #emit ADD.C     12
                #emit ADD
                #emit LOAD.I
                #emit PUSH.pri
            }
            
            #emit PUSH.C        256
            #emit PUSH.C        buffer
            #emit PUSH.S        id
            #emit LOAD.S.pri    8
            #emit ADD.C         args_diff
            #emit PUSH.pri
            #emit SYSREQ.C      RenderTemplate
            #emit LCTRL         5
            #emit SCTRL         4
        }
        else
        {
            RenderTemplate(id, buffer, sizeof buffer);
        }
        return str_new(buffer);
    #endif
}
#endif