Re: gprolog.h

[Erick Alphonse]

hello,

> 1. Why when I compile It says error in gprolog.h? (It says, error parse 
> before template, line 639, I use command g++ -I$QTDIR/include 
> filename1.cpp filename2.cpp moc_filename1.cpp -L$QTDIR/lib -lqt)  And 
> I'm using gnu prolog 1.2.8

use the latest stable release (1.2.16) to fix this problem

> 2. How many methods are there in linking prolog to c++? Because some 
> resources say that we must build a struct and a kind of server in C++ 
> header file. While some people here say that we must put extern C 
> surround the interface code.

here an example to call C++ procedures from gprolog (should compile if 
you modify gprolog.h as I told you before). Note that you need to 
specify int as return value instead of bool. See the gplc doc to compile 
your .cpp with g++ (as exemplified below).

> test.pl
> :- foreign(pred1(+term),[return(boolean)]).
> :- foreign(pred2(+term),[return(boolean)]).
>
> pred1.cpp
> #include "gprolog.h"
>
> extern "C"
> int pred1(PlTerm p) {
>   return true;
> }
>
> pred2.cpp
> #include "gprolog.h"
>
> extern "C"
> int pred2(PlTerm p) {
>   return true;
> }
>
> 1022# gplc --c-compiler g++ -L '-lstdc++' test.pl pred1.cpp pred2.cpp -o
> test

Regards,
Erick.