agglovar.meta.decorators

Decorators for common functionality.

Defines several decorators for adding common functionality to classes and methods.

Decorators include:

  • immutable: Make a class immutable after __init__ completes.

  • lockable: Sets a lock flag (o.is_locked) and provides a lock() method and on optional unlock() method when the

    lock is reversible. The meaning of the lock is up to the class using lockable. Object attributes are immutable while locked (can be disabled) or are always immutable (immutable flag).

These decorators use instance variables to track state, which are automatically when they collide with variables defined in the decorated class.

Functions

immutable([cls])

Make a class immutable after __init__ completes.

lockable([cls, reversible, attrs, immutable, var_name])

Make a class lockable so that it is immutable while locked.

Module Contents

agglovar.meta.decorators.immutable(cls=None)

Make a class immutable after __init__ completes.

agglovar.meta.decorators.lockable(cls=None, *, reversible: bool = False, attrs: bool = True, immutable: bool = False, var_name: str = '_lock')

Make a class lockable so that it is immutable while locked.

# Creates a lock variable that can be checked to see if the object is locked. Semantics of what “locked” means is defined by the class using this decorator. If “attrs” is True, then object attributes cannot be modified while the object is locked. If “immutable” is True, then object attributes cannot be modified at any time.

A lock variable is added to the class with name var_name. If the class defines a variable with the same name, it will be renamed to avoid conflicts. For immutable objects, a flag is added to the object so __init__ can modify attributes, and the flag is removed after __init__ completes. The flag is called “_lockable_in_init”, which is also renamed to avoid collisions.

Parameters:

  • reversible – If True, allow object to be unlocked. Adds an “unlock()” method.

  • attrs – If True, attributes cannot be modified while the object is locked.

  • immutable – If True, class attributes are always immutable whether or not the instance is locked.

  • var_name – Lock variable name. Change if “_lock” is already used by the class.