SWI-cpp2.h is not complete; it needs‘fileSWI-cpp2.cpp
to implement some functions. The easiest way of taking care of this is
to add
#include <SWI-cpp2.cpp> in your "main" file;
alternatively, you can create another source file that contains the
"include" statement.
The easiest way of porting from SWI-cpp.h to SWI-cpp2.h
is to change the #include "SWI-cpp.h" to #include
"SWI-cpp2.h" and look at the warning and error messages. Where
possible, version 2 keeps old interfaces with a "deprecated" flag if
there is a better way of doing things with version 2.
For convenience when calling PL_*() functions, the Plx_*() wrapper
functions add error checking. Also, most of the PL_*() functions that
work with term_t, atom_t, etc. have
corresponding methods in PlTerm, PlAtom, etc.
Here is a list of typical changes:
- Replace PlTerm() constructor with
PlTerm_var() for uninstantiated variables,
PlTerm_atom(a) for atoms, PlTerm_term_t(t) for the raw
term_t, PlTerm_integer(i),
PlTerm_float(v), or PlTerm_pointer(p).
- Examine uses of
char* or wchar_t and
replace them by
std::string or std::wstring if appropriate.
For example, cout << "Hello " <<
A1.as_string().c_str()() << endl can be replaced by cout
<< "Hello " << A1.as_string() << endl. In
general, std::string is safer than char*
because the latter can potentially point to freed memory.
- Instead of returning
false from a predicate for
failure, you can do throw PlFail(). This mechanism
is also used by
PlCheckFail(rc). Note that throwing an exception is significantly
slower than returning false, so performance-critical code
should avoid PlCheckFail(rc).
- You can use the PlCheck_PL(rc) to check the return code from
a function in
SWI-Prolog and throw a PlFail
exception to short-circuit execution and return failure (false)
to Prolog (or throw a PlException if there was a Prolog
error.
PlAtom::handle has been replaced by PlAtom::C_.
PlTerm::ref has been replaced by PlAtom::C_.
PlFunctor::functor has been replaced by PlAtom::C_.
- The operator
=unify_XXX‘methods (PlTerm::unify_term(t2),
PlTerm::unify_atom(a),
etc.).
- The various "cast" operators have been deprecated or deleted; you
should use the various "getter" methods. For example,
static_cast<char*>(t) is replaced by t.as_string().c_str();
static_cast<int32_t>(t) is replaced by t.as_int32_t().
- It is recommended that you do not use
int or
long because of problems porting between Unix and Windows
platforms; instead, use int32_t, int64_t,
uint32_t, uint64_t, etc.
