marshal --- 内部使用向けの Python オブジェクト直列化

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. 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.

警告

marshal モジュールは、誤ったデータや悪意を持って作成されたデータに対する安全性を考慮していません。信頼できない、もしくは認証されていない出所からのデータを非整列化してはなりません。

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, 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).

bytes-like オブジェクトを操作する関数と同様に、ファイルの読み書きを行う関数が提供されています。

このモジュールでは、以下の関数が定義されています。

marshal.dump(value, file[, version])

開かれたファイルに値を書き込みます。値はサポートされている型でなくてはなりません。file は書き込み可能な バイナリファイル である必要があります。

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().

version 引数は dump が使用するデータフォーマットを指定します (下記を参照してください)。

引数 value, version を指定して 監査イベント marshal.dumps を送出します。

marshal.load(file)

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. The file must be a readable binary file.

引数無しで 監査イベント marshal.load を送出します。

注釈

サポートされていない型を含むオブジェクトが dump() で整列化されている場合、 load() は整列化不能な値を None で置き換えます。

バージョン 3.10 で変更: 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.

marshal.dumps(value[, version])

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.

version 引数は dumps が使用するデータフォーマットを指定します (下記を参照してください)。

引数 value, version を指定して 監査イベント marshal.dumps を送出します。

marshal.loads(bytes)

Convert the bytes-like object to a value. If no valid value is found, raise EOFError, ValueError or TypeError. Extra bytes in the input are ignored.

引数 bytes を指定して 監査イベント marshal.loads を送出します。

バージョン 3.10 で変更: 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.

これに加えて、以下の定数が定義されています:

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.

脚注