Advanced serialization library for Python 2.7+

Tickle is a library that allows one to serialize more advanced types, such as lambdas, modules and builtins. It mirrors the pickle module with more advanced features.

It is coded entirely in Python, and as such, is completely portable and does not require external C compilation.

1   Features

• Backwards compatible with pickle
• Serialize lambdas
• Serialize module objects
• Serialize builtins

2   Installation

Simply install using pip:

$ pip install --upgrade tickle

(If pip installation fails for some reason, you can try easy_install tickle as a fallback.)

2.1   Python version

An up-to-date Python 2.x distribution is recommended. Development has been done and tested on Python 2.7, specifically 2.7.13.

2.2   Requirements

No other packages are required for this project to run.

2.3   Unstable version

You can also instead of the latest the latest unreleased development version directly from the develop branch on Bitbucket.

It is a work-in-progress of a future stable release so the experience might be not as smooth.

With pip:

$ pip install --upgrade 'https://bitbucket.org/overridelogic/tickle/get/develop.tar.gz'

3   Reference

3.1   Usage

Usage is pretty similar to the pickle module:

import tickle

value = 42
func = lambda x: value + x

serialized = tickle.dumps(func)
deserialized = tickle.loads(serialized)

assert deserialized(10) == 52

3.2   Limitations

Due to the nature of how Python handles closures, there are some limitations to the library. First and foremost, deserialized objects are copies of the original objects, which means that:

import tickle

class MyObject(object):
    def __eq__(self):
        return self.__class__.__name__ == other.__class__.__name__ and \
            self.__dict__ == other.__dict__

inst = MyObject()
func = lambda: inst

serialized = tickle.dumps(func)
deserialized = tickle.loads(serialized)

assert func() is inst                        # works
assert isinstance(deserialized(), MyObject)  # works
assert deserialized() is inst                # fails

...the inst object is serialized into the scope of the serialized object with its state saved at the time of serialization. The deserializer creates a copy of the original object. They are equal, but they are not the same object.

3.3   Extending

With support from both pickle and tickle, there will rarely be a need to extend this library.

However, if it is required, one can extend the Ticklable class and register a custom type for dispatch:

import tickle

class MyClass(object):
    pass

class MyClassTicklable(tickle.Ticklable):
    def __getstate__(self):
        """returns the number of time the object has been serialized"""
        try:
            return self.data.count
        except AttributeError:
            return 0

    def __setstate__(self, data):
        """increase the counter by one at each deserialization"""
        self.data = MyClass()
        self.data.count = data + 1

# register the handler for this type
tickle.dispatch[MyClass] = MyClassTicklable

inst = MyClass()

serialized = tickle.dumps(inst)
inst = tickle.loads(serialized)
assert inst.count == 1

serialized = tickle.dumps(inst)
inst = tickle.loads(serialized)
assert inst.count == 2

How it works:

• the __getstate__ method has access to the self.data attribute, which contains the object to be serialized. It produces data relevant to deserialization.
• the _setstate__ method accepts the data argument, which is the output the of __getstate__ call. It sets the self.data attribute to the resulting object.

4   Contributing

Contributions are always welcome. If you want to contribute:

• Fork the project
• Test your code (see below)
• Push your code
• Submit a pull request

4.1   Testing

Contributions must pass both the tests and styling guidelines. Before submitting a patch, make sure you run:

$ ./setup.py flake8
$ ./setup.py test

5   About the project

5.1   Change log

See CHANGELOG.

5.2   Licence

MIT License: see LICENSE.

5.3   Authors

Francis Lacroix @francislacroix created tickle while at OverrideLogic.