Documentation¶

This module contains metaclasses which limit the changing member variables of a class once it has been instantiated – that is, after the __init__ function.

The level of access restriction is governed by the attr_mod_ctrl attribute of the class. The possible values for this variable are 'const', 'all', 'new' or 'none'.

attr_mod_ctrl == 'const' prohibits any kind of change to the instance attributes, and also prohibits changing the attr_mod_ctrl variable.
attr_mod_ctrl == 'all' prohibits any changes to the instance attributes, but the attr_mod_ctrl itself can be changed
attr_mod_ctrl == 'new' prohibits the creation of new attributes and deletion of existing ones.
attr_mod_ctrl == 'none' does nothing.

Note

The functionality provided in this module should not be used for security purposes. It is intended only for avoiding accidental changes in attributes, and is in no way guarded against malicious attacks.

class fsc.locker.ConstLocker(name, bases, attrs)¶: Locker metaclass setting attr_mod_ctrl to 'all'.

class fsc.locker.Locker(name, bases, attrs)¶: Locker metaclass setting attr_mod_ctrl to 'new'.

class fsc.locker.OpenLocker(name, bases, attrs)¶: Locker metaclass setting attr_mod_ctrl to 'none'.

class fsc.locker.SuperConstLocker(name, bases, attrs)¶: Locker metaclass setting attr_mod_ctrl to 'const'.

fsc.locker.change_lock(instance, set_to='none')[source]¶: Context manager to set the lock type to one of 'all', 'new' or 'none'. This does not work for SuperConstLocker classes since their lock type cannot be changed, and the lock type cannot be changed to 'const' because it could not be changed back.