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Code: Alles auswählen

class foo:
	def __init__(self, data='initial data', oldfoo=None):
		if oldfoo:
			self.data = oldfoo.data
		if data:
			self.data = data
			
	def __str__(self):
		return 'my data: ' + self.data	
		

if __name__=='__main__':
	f = foo()
	print f
	
	g = foo('new data')
	print g
	
	h = foo('', g)
	print h

Code: Alles auswählen

class Table(dict):
    """Simplified version of frozendict from 
    http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/414283
    
    This implementation is not hashable nor does it try to be.
    It is meant to be used as a drop-in replacement for 'dict'
    and throws AttributeErrors when trying to change it.
    
    Do not expect absolute security from this code, it is only
    meant to catch errors when one mistakenly alters keys in
    this object instead of creating a new Table object based
    on this one.
    
    To create a new Table based on this one use
    >>> Table(old_table, new_key='new_value')
    >>> # or
    >>> Table(old_table, { 'new_key' : 'new_value' })"""

    def _blocked_attribute(obj):
        """This is called when trying to access a attribute which
        modifies the state of this object"""
        # blocked, complain
        raise AttributeError("A Table cannot be modified")
   
    # turn _blocked_attribute into a property
    _blocked_attribute = property(_blocked_attribute)

    # overwrite modifying methods with _blocked_attribute
    __delitem__ = __setitem__ = clear = _blocked_attribute
    pop = popitem = setdefault = update = _blocked_attribute

    def __repr__(self):
        """Display the contents of the Table"""
        return "Table(%s)" % dict.__repr__(self)

    def update(table, updates, *args, **kwargs):
        """Updates a Table environment - it does not alter the Table,
        instead it returns a new Table with the changes applied"""
        # create a new empty dictionary to hold all values
        new_table = dict()
        # choin both dict-like objects together
        all_items = itertools.chain(table.iteritems(), updates.iteritems())

        # add all keys to the dictionary
        for key, value in all_items:
            new_table[key] = value

        # convert the dictionary into a Table and return
        return Table(new_table)

Code: Alles auswählen

h = foo(g.data)

Code: Alles auswählen

class foo:
	def __init__(self, data=('initial data','another'), oldfoo=None):
		if oldfoo:
			allmethods = [method for method in dir(oldfoo)]
			for m in allmethods:
				notclass = str(m).find('__') == -1 # isClassMethod?
				if not callable(getattr(oldfoo, m)) and notclass:
					setattr(self,m,(getattr(oldfoo,m)))
		
		if data:
			self.data = data
			
	def __str__(self):
		s = ''
		for d in self.data: s+=' ' + str(d)
		return s

if __name__=='__main__':
	f = foo()
	print 'f: ', f
	
	g = foo(('new data','second'))
	print 'g: ', g
	
	h = foo('', g)
	print 'h: ', h