classattr 1.0.5

classattr provides tools to manage class and object attributes

classattr package

This package provides tools to manage objects attributes.

It has been made tu be used as a parent class in order to deal with default values for some attributes.

Installation

pip install classattr

Class and object attibutes

For example, you'd like to program a Dot class. Dots attributes are x and y coordinates, diameter and color of the dot.

Most of the time, x and y coordinates depend of the dot but diameter and color are the same.

You can program it in python this way:

class Dot:
	diameter = 2
	color = 'blue'
	
	def __init__(self,x,y):
		self.x = x
		self.y = y
		
	def __repr__(self):
		return f'x = {self.x}, y = {self.y}, diameter = {self.diameter}, color = {self.color}'

>>> d1 = Dot(2,3)
>>> d2 = Dot(-1,4)
>>> d3 = Dot(6,11)
>>> d1
x = 2, y = 3, diameter = 2, color = blue

If you want to change d2 color:

>>> d2.color = 'yellow'
>>> d2
x = -1, y = 4, diameter = 2, color = yellow
>>> d3
x = 6, y = 11, diameter = 2, color = blue

And if you want to turn default color from blue to black:

>>> Dot.color = 'black'
>>> d1
x = 2, y = 3, diameter = 2, color = black
>>> d2
x = -1, y = 4, diameter = 2, color = yellow		
>>> d3
x = 6, y = 11, diameter = 2, color = black

With classattr

To program the above example with classattr, you can do it this way:

from classattr import ClassAttr, RAISE, FORCE

class Dot(ClassAttr):

    ## class atribute, can be default value
    x = 0
    y = 0
    radius = 2
    color = 'blue'

    def __init__(self,attr = {},mode=RAISE,**kwargs):

        ClassAttr.__init__(self,attr,mode,**kwargs)

Then to create new dots, you can use syntax below:

>>> d1 = Dot(x=2,y=3)
>>> d2 = Dot(x=-1,y=4,color='yellow')
>>> d3 = Dot(x=6,y=11)

or use a dictionary

>>> d1 = Dot({'x':2,'y':3})
>>> d2 = Dot({'x':-1,'y':4,'color':'yellow'})
>>> d3 = Dot({'x':6,'y':11})

To change an attribute's value :

>>> d1.set(x=8)

or

>>> d1.set({'x':8})

To change an attribute's default value :

>>> Dot.set_default(color='lightblue')

or

>>> Dot.set_default({'color':'lightblue'})

To get attributes values :

>>> d1.get()
{'x': 8, 'y': 3, 'radius': 2, 'color': 'lightblue'}
>>> d2.get()
{'x': -1, 'y': 4, 'radius': 2, 'color': 'yellow'}
>>> d3.get()
{'x': 6, 'y': 11, 'radius': 2, 'color': 'lightblue'}

To get only one attribute :

>>> d1.get('color')
'lightblue'

And to get some :

>>> d1.get(['color','radius'])
{'color': 'lightblue', 'radius': 2}

To get attributes list :

d1.get_keys()
['color', 'radius', 'x', 'y']

To create a new attribute, use mode :

MODE :

RAISE (default value) raise an exception error if attribute doesn't already exist IGNORE ignore attribute doesn't already exist FORCE create the new attribute

>>> d1.set({'z':8},mode=FORCE)
>>> d1.get()
{'x': 8, 'y': 3, 'radius': 2, 'color': 'lightblue', 'z': 8}