__init__(self, [<attrname>=<value, rule or dict>], ...) -> None

>>> class A(cells.Model):
...     x = cells.makecell(value=1)
... 
>>> a1 = A()
>>> a1.x
1

>>> a2 = A(x="blah")
>>> a2.x
'blah'

>>> class B(cells.Model):
...     x = cells.makecell(rule=lambda s,p: 3 * s.y)
...     y = cells.makecell(value=2)
... 
>>> b = B()
>>> b.x
6

>>> b.y = 1
>>> b.x
3

>>> b = B(y=10)
>>> b.x
30

>>> b.y
10

>>> b = B(x={'celltype': cells.RuleThenInputCell})
>>> b.x
6

>>> b.y
2

>>> b.x = 5
>>> b.x
5

>>> b.y = 1
>>> b.x
5

Parameters:

• attrname - The name of the attribute you wish to override. If this is set to a callable, it will override the rule for the cell. If it's set to a dictionary with one or more of 'rule', 'value', or 'celltype', those attributes will be overridden in the cell. Otherwise, it will override the value of the target cell.

Overrides: object.__init__

Raises:

• NonCellSetError - If you try to set a non-cell attribute

Overrides: object.__setattr__

>>> import cells
>>> class A(cells.Model):
...     x = cells.makecell(value=4)
... 
>>> @A.observer(attrib="x", newvalue=lambda a: a % 2)
... def odd_x_obs(model):
...     print "New value of x is odd!"
... 
>>> a = A()
>>> a.x
4

>>> a.x = 5
New value of x is odd!

>>> a.x = 42
>>> a.x = 11
New value of x is odd!

Parameters:

• attrib - An attribute name to attach the observer to
• oldvalue - A function to run on the now-out-of-date value of a cell which changed in this datapulse; if the function returns True, the observer will fire. The signature for the function must be f(val) -> bool
• newvalue - A function to run on up-to-date value; if the function returns True, the observer will fire. The signature for the function must be f(val) -> bool

Returns:

decorator