# `marshal` --- Internal Python object serialization

This module contains functions that can read and write Python values in a binary format. The format is specific to Python, but independent of machine architecture issues (e.g., you can write a Python value to a file on a PC, transport the file to a Mac, and read it back there). Details of the format are undocumented on purpose; it may change between Python versions (although it rarely does). [1]

This is not a general "persistence" module. For general persistence and transfer of Python objects through RPC calls, see the modules `pickle` and `shelve`. The `marshal` module exists mainly to support reading and writing the "pseudo-compiled" code for Python modules of `.pyc` files. Therefore, the Python maintainers reserve the right to modify the marshal format in backward incompatible ways should the need arise. The format of code objects is not compatible between Python versions, even if the version of the format is the same. De-serializing a code object in the incorrect Python version has undefined behavior. If you're serializing and de-serializing Python objects, use the `pickle` module instead -- the performance is comparable, version independence is guaranteed, and pickle supports a substantially wider range of objects than marshal.

Avertissement

N'utilisez pas le module `marshal` pour lire des données erronées ou malveillantes. Ne démantelez jamais des données reçues d'une source non fiable ou non authentifiée.

Not all Python object types are supported; in general, only objects whose value is independent from a particular invocation of Python can be written and read by this module. The following types are supported: booleans, integers, floating-point numbers, complex numbers, strings, bytes, bytearrays, tuples, lists, sets, frozensets, dictionaries, and code objects (if allow_code is true), where it should be understood that tuples, lists, sets, frozensets and dictionaries are only supported as long as the values contained therein are themselves supported. The singletons `None`, `Ellipsis` and `StopIteration` can also be marshalled and unmarshalled. For format version lower than 3, recursive lists, sets and dictionaries cannot be written (see below).

Il existe des fonctions de lecture-écriture de fichiers ainsi que des fonctions opérant sur des objets octet.

Le module définit ces fonctions :

marshal.dump(value, file, version=version, /, *, allow_code=True)

  Écrit la valeur sur le fichier ouvert. La valeur doit être un type pris en charge. Le fichier doit être un fichier binaire ouvert en écriture.

  If the value has (or contains an object that has) an unsupported type, a `ValueError` exception is raised --- but garbage data will also be written to the file. The object will not be properly read back by `load()`. Code objects are only supported if allow_code is true.

  L'argument version indique le format de données que le `dump` doit utiliser (voir ci-dessous).

  Raises an auditing event `marshal.dumps` with arguments `value`, `version`.

  Modifié dans la version 3.13: Added the allow_code parameter.

marshal.load(file, /, *, allow_code=True)

  Read one value from the open file and return it. If no valid value is read (e.g. because the data has a different Python version's incompatible marshal format), raise `EOFError`, `ValueError` or `TypeError`. Code objects are only supported if allow_code is true. The file must be a readable binary file.

  Raises an auditing event `marshal.load` with no arguments.

  Note

  Si un objet contenant un type non pris en charge a été dé-compilé avec `dump()`, `load()` remplacera le type non « dé-compilable » par `None`.

  Modifié dans la version 3.10: This call used to raise a `code.__new__` audit event for each code object. Now it raises a single `marshal.load` event for the entire load operation.

  Modifié dans la version 3.13: Added the allow_code parameter.

marshal.dumps(value, version=version, /, *, allow_code=True)

  Return the bytes object that would be written to a file by `dump(value, file)`. The value must be a supported type. Raise a `ValueError` exception if value has (or contains an object that has) an unsupported type. Code objects are only supported if allow_code is true.

  L'argument version indique le format de données que `dumps` doivent utiliser (voir ci-dessous).

  Raises an auditing event `marshal.dumps` with arguments `value`, `version`.

  Modifié dans la version 3.13: Added the allow_code parameter.

marshal.loads(bytes, /, *, allow_code=True)

  Convert the bytes-like object to a value. If no valid value is found, raise `EOFError`, `ValueError` or `TypeError`. Code objects are only supported if allow_code is true. Extra bytes in the input are ignored.

  Raises an auditing event `marshal.loads` with argument `bytes`.

  Modifié dans la version 3.10: This call used to raise a `code.__new__` audit event for each code object. Now it raises a single `marshal.loads` event for the entire load operation.

  Modifié dans la version 3.13: Added the allow_code parameter.

De plus, les constantes suivantes sont définies :

marshal.version

  Indicates the format that the module uses. Version 0 is the historical format, version 1 shares interned strings and version 2 uses a binary format for floating-point numbers. Version 3 adds support for object instancing and recursion. The current version is 4.

Notes

[1]

Le nom de ce module provient d'un peu de terminologie utilisée par les concepteurs de Modula-3 (entre autres), qui utilisent le terme marshalling pour l'envoi de données sous une forme autonome. À proprement parler, to marshal signifie convertir certaines données d'une forme interne à une forme externe (dans une mémoire tampon RPC par exemple) et unmarshalling désigne le processus inverse.