network safe functions that always store their data in a format that is readable on any computer at a small cost of speed. These functions are named nstore, nfreeze, etc. There are no "n" functions for deserializing these structures — the regular thaw and retrieve deserialize structures serialized with the "n" functions and their machine-specific equivalents. PHP PHP originally implemented serialization through the built-in serialize() and unserialize() functions. PHP can serialize any of its data types except resources (file pointers, sockets, etc.). The built-in unserialize() function is often dangerous when used on completely untrusted data. For objects, there are two "magic methods" that can be implemented within a class — __sleep() and __wakeup() — that are called from within serialize() and unserialize(), respectively, that can clean up and restore an object. For example, it may be desirable to close a database connection on serialization and restore the connection on deserialization; this functionality would be handled in these two magic methods. They also permit the object to pick which properties are serialized. Since PHP 5.1, there is an object-oriented serialization mechanism for objects, the Serializable interface. Prolog Prolog's term structure, which is the only data structure of the language, can be serialized out through the built-in predicate write_term/3 and serialized-in through the built-in predicates read/1 and read_term/2. The resulting stream is uncompressed text (in some encoding determined by configuration of the target stream), with any free variables in the term represented by placeholder variable names. The predicate write_term/3 is standardized in the ISO Specification for Prolog (ISO/IEC 13211-1) on pages 59 ff. ("Writing a term, § 7.10.5"). Therefore it is expected that terms serialized-out by one implementation can be serialized-in by another without ambiguity or surprises. In practice, implementation-specific extensions (e.g. SWI-Prolog's dictionaries) may use non-standard term structures, so interoperability may break in edge cases. As examples, see the corresponding manual pages for SWI-Prolog, SICStus Prolog, GNU Prolog. Whether and how serialized terms received over the network are checked against a specification (after deserialization from the character stream has happened) is left to the implementer. Prolog's built-in Definite Clause Grammars can be applied at that stage. Python The core general serialization mechanism is the pickle standard library module, alluding to the database systems term pickling to describe data serialization (unpickling for deserializing). Pickle uses a simple stack-based virtual machine that records the instructions used to reconstruct the object. It is a