31.13. pickletools — Tools for pickle developers

Source code: Lib/pickletools.py

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This module contains various constants relating to the intimate details of the pickle module, some lengthy comments about the implementation, and a few useful functions for analyzing pickled data. The contents of this module are useful for Python core developers who are working on the pickle; ordinary users of the pickle module probably won’t find the pickletools module relevant.

31.13.1. Command line usage

New in version 3.2.

When invoked from the command line, python -m pickletools will disassemble the contents of one or more pickle files. Note that if you want to see the Python object stored in the pickle rather than the details of pickle format, you may want to use -m pickle instead. However, when the pickle file that you want to examine comes from an untrusted source, -m pickletools is a safer option because it does not execute pickle bytecode.

For example, with a tuple (1, 2) pickled in file x.pickle:

$ python -m pickle x.pickle
(1, 2)

$ python -m pickletools x.pickle
    0: \x80 PROTO      3
    2: K    BININT1    1
    4: K    BININT1    2
    6: \x86 TUPLE2
    7: q    BINPUT     0
    9: .    STOP
highest protocol among opcodes = 2

31.13.1.1. Command line options

-a, --annotate

Annotate each line with a short opcode description.

-o, --output=<file>

Name of a file where the output should be written.

-l, --indentlevel=<num>

The number of blanks by which to indent a new MARK level.

-m, --memo

When multiple objects are disassembled, preserve memo between disassemblies.

-p, --preamble=<preamble>

When more than one pickle file are specified, print given preamble before each disassembly.

31.13.2. Programmatic Interface

pickletools.dis(pickle, out=None, memo=None, indentlevel=4, annotate=0)

Outputs a symbolic disassembly of the pickle to the file-like object out, defaulting to sys.stdout. pickle can be a string or a file-like object. memo can be a Python dictionary that will be used as the pickle’s memo; it can be used to perform disassemblies across multiple pickles created by the same pickler. Successive levels, indicated by MARK opcodes in the stream, are indented by indentlevel spaces. If a nonzero value is given to annotate, each opcode in the output is annotated with a short description. The value of annotate is used as a hint for the column where annotation should start.

New in version 3.2: The annotate argument.

pickletools.genops(pickle)

Provides an iterator over all of the opcodes in a pickle, returning a sequence of (opcode, arg, pos) triples. opcode is an instance of an OpcodeInfo class; arg is the decoded value, as a Python object, of the opcode’s argument; pos is the position at which this opcode is located. pickle can be a string or a file-like object.

pickletools.optimize(picklestring)

Returns a new equivalent pickle string after eliminating unused PUT opcodes. The optimized pickle is shorter, takes less transmission time, requires less storage space, and unpickles more efficiently.