JSON-Serializable IPython Traitlets
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README.rst

serializable-traitlets

Serializable IPython Traitlets

serializable-traitlets (imported as straitlets) is a Python 2/3 compatible library providing a restricted subset of the classes from IPython Traitlets. Within our restricted subset, we inherit all the benefits of using regular traitlets, including static type declarations, dynamic default generators, and attribute observers/validators.

By supporting only a limited (though still expressive) subset of Python objects, however, we gain the ability to serialize and deserialize instances of Serializable to and from various formats, including:

  1. JSON
  2. YAML
  3. base64-encoded strings

These properties make Serializables well-suited for configuration in environments where objects need to be transferred between processes.

straitlets also provides users the ability to specify example values for traits. If all traits of a Serializable class have examples (or default values) provided, then we can auto-generate an example for the parent class, and we can resursively generate examples for nested classes.

Usage

Basic Usage:

In [1]: from straitlets import Serializable, Integer, Dict, List
In [2]: class Foo(Serializable):
   ...:     my_int = Integer()
   ...:     my_dict = Dict()
   ...:     my_list = List()

In [3]: instance = Foo(my_int=3, my_dict={'a': [1, 2], 'b': (3, 4)}, my_list=[5, None])

In [4]: print(instance.to_json())
{"my_int": 3, "my_dict": {"a": [1, 2], "b": [3, 4]}, "my_list": [5, null]}

In [5]: print(instance.to_yaml())
my_dict:
a:
- 1
- 2
b:
- 3
- 4
my_int: 3
my_list:
- 5
- null

Autogenerating Example Values:

from straitlets import Serializable, Integer, Instance

class Point(Serializable):
    x = Integer().example(0)
    y = Integer().example(0)


class Vector(Serializable):
    # We can automatically generate example values for attributes
    # declared as Instances of Serializable.
    head = Instance(Point)

    # Per-attribute overrides are still supported.
    tail = Instance(Point).example(Point(x=1, y=3))

print(Vector.example_instance().to_yaml())
# head:
#   x: 0
#   y: 0
# tail:
#   x: 1
#   y: 3