context manager to temporary set/delete object's attributes

attributes.py

DELETE_ATTRIBUTE = object()
@contextmanager
def attributes(*values):
    """ context manager to temporary set/delete object's attributes
       
    :param values: tulples of (target, name, value)
    Es.
    
    
    with attributes((django.contrib.admin.ModelAdmin, 'list_per_page', 200)):
        ...

    with attributes((django.contrib.admin.ModelAdmin, 'list_per_page', DELETE_ATTRIBUTE)):
        ...
    
    """
    def set(target, name, value):
        if value is DELETE_ATTRIBUTE:
            delattr(target, name)
        else:
            setattr(target, name, value)
        
    backups = []
    
    for target, name, value in values:
        backups.append((target, name, getattr(target, name, DELETE_ATTRIBUTE)))
        set(target, name, value)
    yield
    for target, name, value in backups:
        set(target, name, value)