Installation

Available as a PyPI package:

pip install candv

Brief overview

The most basic definition of constants:

from candv import Constants
from candv import SimpleConstant

class TEAM(Constants):
  RED  = SimpleConstant()
  BLUE = SimpleConstant()

And usage:

TEAM.RED                 # <constant 'TEAM.RED'>
TEAM['RED']              # <constant 'TEAM.RED'>
TEAM.get('RED')          # <constant 'TEAM.RED'>
TEAM.get('GREEN')        # None
TEAM.RED.name            # 'RED'
TEAM.RED.full_name       # 'TEAM.RED'
TEAM.RED.to_primitive()  # {'name': 'RED'}
TEAM.RED.container       # <constants container 'TEAM'>

TEAM                     # <constants container 'TEAM'>
TEAM.name                # 'TEAM'
TEAM.full_name           # 'TEAM'
len(TEAM)                # 2
TEAM.has_name('RED')     # True

TEAM.names()             # ['RED', 'BLUE']
TEAM.iternames()         # <odict_iterator object at 0x7f451013e0e0>

TEAM.constants()         # [<constant 'TEAM.RED'>, <constant 'TEAM.BLUE'>]
TEAM.iterconstants()     # <odict_iterator object at 0x7f45100f3450>

TEAM.items()             # [('RED', <constant 'TEAM.RED'>), ('BLUE', <constant 'TEAM.BLUE'>)]
TEAM.iteritems()         # <odict_iterator object at 0x7f451013bdb0>

TEAM.to_primitive()      # {'name': 'TEAM', 'items': [{'name': 'RED'}, {'name': 'BLUE'}]}

Using with values:

from candv import Values
from candv import ValueConstant

class TEAM(Values):
  RED  = ValueConstant(1)
  BLUE = ValueConstant(2)


TEAM.values()            # [1, 2]
TEAM.itervalues()        # <map object at 0x7f450ffdb1c0>

TEAM.get_by_value(1)     # <constant 'TEAM.RED'>
TEAM.filter_by_value(1)  # [<constant 'TEAM.RED'>]

TEAM.RED.value           # 1
TEAM.RED.to_primitive()  # {'name': 'RED', 'value': 1}

Using with human-readable names:

from candv import Constants
from candv import VerboseConstant

class Countries(Constants):
  au = VerboseConstant("Australia")
  uk = VerboseConstant("United Kingdom")
  us = VerboseConstant("United States")


Countries.au.name            # 'au'
Countries.au.verbose_name    # 'Australia'
Countries.au.help_text       # None
Countries.au.to_primitive()  # {'name': 'au', 'verbose_name': 'Australia', 'help_text': None}

With values and names:

from candv import Values
from candv import VerboseValueConstant

class SkillLevel(Values):
  rki = VerboseValueConstant(0, "rookie")
  avg = VerboseValueConstant(1, "average")
  vtn = VerboseValueConstant(2, "veteran")
  ace = VerboseValueConstant(3, "ace")


SkillLevel.avg.value           #  1
SkillLevel.avg.name            # 'avg'
SkillLevel.avg.full_name       # 'SkillLevel.avg'
SkillLevel.avg.verbose_name    # 'average'
SkillLevel.avg.help_text       # None
SkillLevel.avg.to_primitive()  # {'name': 'avg', 'value': 1, 'verbose_name': 'average', 'help_text': None}

Plays well with verboselib or, say, Django translation strings:

from candv import Constants
from candv import VerboseConstant

from verboselib import Translations


translations = Translations(
  domain="the_app",
  locale_dir_path="locale",
)
_ = translations.gettext_lazy


class UnitType(Constants):
  aircraft = VerboseConstant(_("aircraft"))
  ship     = VerboseConstant(_("ship"))
  train    = VerboseConstant(_("train"))
  vehicle  = VerboseConstant(_("vehicle"))

Supports custom methods:

from candv import Constants
from candv import SimpleConstant

class SupportedLanguages(Constants):
  en = SimpleConstant()
  ru = SimpleConstant()

  @classmethod
  def get_default(cls):
    return cls.en


SupportedLanguages.get_default()  # <constant 'SupportedLanguages.en'>

And custom types of constants:

from candv import Constants
from candv import SimpleConstant
from candv import with_constant_class

class MissionStatus(SimpleConstant):
  ...

class MissionStatuses(with_constant_class(MissionStatus), Constants):
  not_loaded = MissionStatus()
  loaded     = MissionStatus()
  playing    = MissionStatus()

It’s also possible to define hierarchies:

from candv import Constants
from candv import SimpleConstant

class STATUS(Constants):
  SUCCESS = SimpleConstant()
  ERROR   = SimpleConstant().to_group(Constants,

    INVALID   = SimpleConstant(),
    NOT_FOUND = SimpleConstant(),
    INTERNAL  = SimpleConstant(),
  )


STATUS.names()                   # ['SUCCESS', 'ERROR']
STATUS.ERROR                     # <constants group 'STATUS.ERROR'>
STATUS.ERROR.full_name           # 'STATUS.ERROR'
STATUS.ERROR.INTERNAL            # <constant 'STATUS.ERROR.INTERNAL'>
STATUS.ERROR.INTERNAL.full_name  # 'STATUS.ERROR.INTERNAL'
STATUS.ERROR.names()             # ['INVALID', 'NOT_FOUND', 'INTERNAL']

More info

Visit the docs for full information.

See django-candv-choices for using as choices in django.

See django-rf-candv-choices for using as choices in django-rest-framework.