candv package

Submodules

candv.core module

Defines base constant and base container for constants.

class candv.core.SimpleConstant

Bases: object

Base class for all constants.

Variables:name (str) – constant’s name: set up automatically and is equal to the name of the container’s attribute

full_name

merge_into_group(group)

Called automatically by the container after group construction.

Note

Redefine this method in all derived classes. Attach all custom attributes and methods to the group here.

Parameters:group – an instance of Constants or of its subclass into which this constant will be merged Returns:None

to_group(group_class, **group_members)

Convert a constant into a constants group.

Parameters:

• group_class (class) – a class of group container which will be created
• group_members – unpacked dict which defines group members

Returns:

a lazy constants group which will be evaluated by the container. Method merge_into_group() will be called during evaluation of the group

Example:

from candv import Constants
from candv import SimpleConstant


class FOO(Constants):
  A = SimpleConstant()
  B = SimpleConstant().to_group(Constants,

    B2 = SimpleConstant(),
    B0 = SimpleConstant(),
    B1 = SimpleConstant(),
  )

to_primitive(*args, **kwargs)

Represent the constant via Python’s primitive data structures.

Changed in version 1.5.0: The context param is replaced by *args and **kwargs.

New in version 1.3.0.

class candv.core.Constants

Bases: object

Base class for creating constants containers.

Each constant defined within the container will remember its creation order.

See an example in constants().

Variables:constant_class – defines a class of constants which a container will store. This attribute MUST be set up manually when you define a new container type. Otherwise container will not be initialized. Default: None Raises:CandvContainerMisusedError – if you try to create an instance of container. Containers are singletons and they cannot be instantiated. Their attributes must be used directly.

constant_class

Defines a top-level class of constants which can be stored by container

alias of SimpleConstant

full_name = 'Constants'

name = 'Constants'

candv.core.with_constant_class(the_class)

Create a mixin class with constant_class attribute.

Allows to set a constant class for constants container outside container itself. This may help to create more readable container definition, e.g.:

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


class CustomConstant(SimpleConstant):
  ...

class FOO(with_constant_class(CustomConstant), Constants):
  A = CustomConstant()
  B = CustomConstant()

>>> FOO.constant_class
<class '__main__.CustomConstant'>

candv.exceptions module

exception candv.exceptions.CandvException

Bases: Exception

Base exception

New in version 1.4.0.

exception candv.exceptions.CandvTypeError

Bases: TypeError, candv.exceptions.CandvException

New in version 1.4.0.

exception candv.exceptions.CandvInvalidGroupMemberError

Bases: candv.exceptions.CandvTypeError

New in version 1.4.0.

exception candv.exceptions.CandvInvalidConstantClass

Bases: candv.exceptions.CandvTypeError

New in version 1.4.0.

exception candv.exceptions.CandvContainerMisusedError

Bases: candv.exceptions.CandvTypeError

New in version 1.4.0.

exception candv.exceptions.CandvConstantAlreadyBoundError

Bases: ValueError, candv.exceptions.CandvException

New in version 1.4.0.

exception candv.exceptions.CandvMissingConstantError

Bases: KeyError, candv.exceptions.CandvException

New in version 1.4.0.

exception candv.exceptions.CandvValueNotFoundError

Bases: ValueError, candv.exceptions.CandvException

New in version 1.4.0.

candv.ext module

Provides extra ready-to-use classes for constructing custom constants.

class candv.ext.VerboseMixin(*args, **kwargs)

Bases: object

Adds verbose_name and help_text attributes to constants.

Arguments must be passed as kwargs.

Parameters:

• verbose_name (str) – optional verbose name
• help_text (str) – optional description

Example:

class CustomConstant(object):

  def __init__(self, arg1, arg2, kwarg1=None):
    pass


class VerboseCustomConstant(VerboseMixin, CustomConstant):

  def __init__(self, arg1, arg2, kwarg1=None, verbose_name=None, help_text=None):
    super().__init__(
      arg1,
      arg2,
      kwarg1=kwarg1,
      verbose_name=verbose_name,
      help_text=help_text,
    )

merge_into_group(group)

Overrides merge_into_group() to add verbose_name with help_text attributes to the target group.

to_primitive(*args, **kwargs)

Changed in version 1.5.0: The context param is replaced by *args and **kwargs.

New in version 1.3.0.

class candv.ext.VerboseConstant(verbose_name=None, help_text=None)

Bases: candv.ext.VerboseMixin, candv.core.SimpleConstant

A constant with optional verbose name and optional help text.

Parameters:

• verbose_name (str) – optional verbose name of the constant
• help_text (str) – optional description of the constant

Variables:

• verbose_name (str) – verbose name of the constant. Default: None
• help_text (str) – verbose description of the constant. Default: None

class candv.ext.ValueConstant(value)

Bases: candv.core.SimpleConstant

A constant with ability to hold arbitrary values.

Parameters:value – a value to attach to constant Variables:value – constant’s value

merge_into_group(group)

Redefines merge_into_group() and adds value attribute to the target group.

to_primitive(*args, **kwargs)

Changed in version 1.5.0: The context param is replaced by *args and **kwargs.

New in version 1.3.0.

class candv.ext.VerboseValueConstant(value, verbose_name=None, help_text=None)

Bases: candv.ext.VerboseMixin, candv.ext.ValueConstant

A constant which can have both verbose name, help text, and a value.

Parameters:

• value – a value to attach to the constant
• verbose_name (str) – an optional verbose name of the constant
• help_text (str) – an optional description of the constant

Variables:

• value – constant’s value
• verbose_name (str) – verbose name of the constant. Default: None
• help_text (str) – verbose description of the constant. Default: None

class candv.ext.Values

Bases: candv.core.Constants

A container for ValueConstant and its derivatives.

Supports getting and filtering constants by their values plus listing values of all constants in container.

constant_class

alias of ValueConstant

classmethod filter_by_value(value)

Get all constants which have given value.

Parameters:value – value of the constants to look for Returns:list of all found constants with given value

full_name = 'Values'

classmethod get_by_value(value)

Get a constant by its value.

Parameters:value – value of the constant to look for Returns:first found constant with given value Raises:CandvValueNotFoundError – if no constant in container has given value

classmethod itervalues()

Get an iterator over values of all constants in the order they were defined.

Same as values() but returns an interator.

Note

Overrides itervalues() since 1.1.2.

name = 'Values'

classmethod values()

List values of all constants in the order they were defined.

Returns:list of values

Example:

from candv import Values
from candv import ValueConstant


class FOO(Values):
  TWO  = ValueConstant(2)
  ONE  = ValueConstant(1)
  SOME = ValueConstant("some string")

>>> FOO.values()
[2, 1, 'some string']

Note

Overrides values() since 1.1.2.

candv.version module

Module contents