1.11.11 The class PlTermv

The class PlTermv represents an array of term-references. This type is used to pass the arguments to a foreign defined predicate, construct compound terms (see PlTerm::PlTerm(const char *name)PlTermv arguments ), and to create queries (see PlQuery).

The only useful member function is the overloading of [], providing (0-based) access to the elements. Range checking is performed and raises a domain_error exception.

The constructors for this class are below. Note that these can be error-prone because there's no distinction between term_t and size_t; the form of the constructor is determined by whether the first argument is an integer (term_t or size_t) or PlTerm.

PlTermv :: PlTermv(size_t size)

Create a new array of term-references, all holding variables.

PlTermv :: PlTermv(size_t size, term_t t0)

Convert a C-interface defined term-array into an instance. Typyically, t0 was created using Pl_new_term_refs(size).

PlTermv :: PlTermv(PlTerm ...)

Create a vector from 1 to 5 initialising arguments. For example:

load_file(const char *file)
{ return PlCall("compile", PlTermv(PlAtom(file)));
}

If the vector has to contain more than 5 elements, the following construction should be used:

{ PlTermv av(10);

  av[0].put_term(PlTerm_atom("hello"));
  av[1].put_term(PlTerm_integer(666));
  ...
}

Important: be sure that all the arguments are of type PlTerm - PlTermv(i) is not the same as PlTermv(PlTerm_integer(i)), and will result in a runtime error.