2.11 The class PlAtom - Supporting Prolog constants (version 2)
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      • A C++ interface to SWI-Prolog
        • A C++ interface to SWI-Prolog (Version 2)
          • The class PlAtom - Supporting Prolog constants (version 2)
            • Direct comparision to char *
            • Direct comparision to PlAtom
            • Extraction of the atom and comparison to PlAtom
            • Extraction of the atom and comparison to char *

2.11.2 Direct comparision to PlAtom

Example:

static PlAtom ATOM_read("read");

PREDICATE(test, 1)
{ if ( A1 == ATOM_read )
    ...;
}

This case raises a type_error if A1 is not an atom. Otherwise it extacts the atom-handle and compares it to the atom-handle of the global PlAtom object. This approach is faster and provides more strict type-checking.