Secure Implementation of Meta-predicates

Meta-predicate Semantics

“…These directives take predicate indicators as arguments and thus support a simpler and user-friendlier solution when compared with the meta_predicate/1 directive. However, we have show in [3] that distinguishing between goals and closures and specifying the exact number of closure additional arguments is necessary to avoid misuse of meta-predicate definitions.…”

“…As in the Prolog directive described above, closures are represented by a non-negative integer. Logtalk uses this information to verify meta-predicate definitions, as discussed in [3]. Logtalk supports a mode/2 predicate directive for specifying the instantiation mode and the type of predicate arguments (plus the predicate determinism).…”

“…This, however, is mostly meaningful for languages such as Logtalk and for Prolog module systems, such as ECLiPSe and Ciao [13], that aim to enforce object and module predicate scope rules. The following set of compilation rules, described and illustrated in detail in [3], contribute to make meta-predicate definitions secure:…”

“…When discussing meta-predicate semantics, it is useful to define the contexts where a meta-predicate is defined, called, and executed. The following definitions are taken from [3] and will be used in this paper:…”

“…When discussing meta-predicate semantics, it is useful to define the contexts where a meta-predicate is defined, called, and executed. The following definitions are taken from [3] and will be used in this paper: Definition context This is the object or module containing the meta-predicate definition. Calling context This is the object or module from which a meta-predicate is called.…”