Compound terms can be viewed as an array of terms with a name and
arity (length). This view is expressed by overloading the []
A type_error is raised if the argument is not compound
and a
domain_error if the index is out of range.
In addition, the following functions are defined:
- PlTerm PlTerm::operator[](int
arg)
- If the
PlTerm is a compound term and arg is
between 1 and the arity of the term, return a new PlTerm
representing the arg-th argument of the term. If PlTerm is
not compound, a
type_error is raised. Id arg is out of range, a
domain_error is raised. Please note the counting from 1
which is consistent to Prolog's arg/3
predicate, but inconsistent to C's normal view on an array. See also
class PlCompound. The following example tests x
to represent a term with first-argument an atom or string equal to gnat.
...,
if ( x[1] == "gnat" )
...
- const char * PlTerm::name()
- Return a
const char * holding the name of the functor of
the compound term. Raises a type_error if the argument is
not compound.
- size_t PlTerm::arity()
- Returns the arity of the compound term. Raises a
type_error
if the argument is not compound.
