Skip to main content

Immutable struct with sane defaults

Project description

Immutable struct built on top of collections.namedtuple with sane defaults


  • Immutable, dictionary-like data structure (Note: istruct is not an immutable version of the existing struct in Python)
  • Minimal
  • Support required and optional fields (with default values)
  • Strictly disallow positional arguments


pip install istruct

Quick Start

First, create an istruct object called person where first_name and last_name are required whereas middle_name, dob and email are optional (with default values specified).

In [1]: from istruct import istruct

In [2]: person = istruct("first_name", "last_name", middle_name="", dob="2000-01-01", email=None)

Then, create an instance of person with first_name, last_name and middle_name.

In [3]: p = person(first_name="Jim", last_name="Raynor", middle_name="Eugene")

In [4]: p
Out[4]: istruct(first_name='Jim', last_name='Raynor', email=None, dob='2000-01-01', middle_name='Eugene')

You can retrieve field values like you would normally do.

In [5]: p.first_name
Out[5]: 'Jim'

In [6]: p.dob
Out[6]: '2000-01-01'

p is immutable, meaning that it cannot be modified after created. Thus, set/delete operations like below would fail, raising an AttributeError.

In [7]: p.first_name = "James"
AttributeError                            Traceback (most recent call last)
<ipython-input-13-681faedb279a> in <module>()
----> 1 p.first_name = "James"

AttributeError: can't set attribute

In [8]: del
AttributeError                            Traceback (most recent call last)
<ipython-input-12-d5c698764d13> in <module>()
----> 1 del

AttributeError: can't delete attribute

istruct only accepts named/keyword arguments. It strictly disallows positional arguments by design.

In [9]: p = person("Jim", "Raynor")
TypeError                                 Traceback (most recent call last)
<ipython-input-6-c0bdbd269e9f> in <module>()
----> 1 p = person("Jim", "Raynor")

/home/microamp/devel/projs/istruct/istruct/ in _istruct(*positional, **attrs)
     49         if positional:
     50             raise TypeError("No positional arguments are allowed in istruct "
---> 51                             "(%d found)" % (len(positional),))
     53         nt = namedtuple(__name__,

TypeError: No positional arguments are allowed in istruct (2 found)

istruct would raise a TypeError when one or more required fields are omitted.

In [10]: p = person(last_name="Raynor")
TypeError                                 Traceback (most recent call last)
<ipython-input-15-451d2add9ee8> in <module>()
----> 1 p = person(last_name="Raynor")

/home/microamp/devel/projs/istruct/ in _istruct(**attrs)
     25     def _istruct(**attrs):
     26         nt = namedtuple(name(), merge_tuples(args, tuple(kwargs.keys())))
---> 27         return nt(**merge_dicts(kwargs, attrs))
     29     return _istruct

TypeError: __new__() missing 1 required positional argument: 'first_name'

Versions Tested

  • Python 2.7
  • Python 3.2
  • Python 3.3
  • Python 3.4
  • PyPy
  • PyPy3


  • Find ways to annotate types



Project details

Download files

Download the file for your platform. If you're not sure which to choose, learn more about installing packages.

Files for istruct, version 0.1.5
Filename, size File type Python version Upload date Hashes
Filename, size istruct-0.1.5.tar.gz (3.4 kB) File type Source Python version None Upload date Hashes View

Supported by

AWS AWS Cloud computing Datadog Datadog Monitoring DigiCert DigiCert EV certificate Facebook / Instagram Facebook / Instagram PSF Sponsor Fastly Fastly CDN Google Google Object Storage and Download Analytics Microsoft Microsoft PSF Sponsor Pingdom Pingdom Monitoring Salesforce Salesforce PSF Sponsor Sentry Sentry Error logging StatusPage StatusPage Status page