Python advanced programming for objects--using __slots__

1.1   Use__slots__1.1.1   binding of class methods

Adding methods on an instance

>>> class Student (object):

... pass

...

>>> def set_age (Self, Age): # define the function as an instance method, note that the self parameter

... self.age = age

...

>>> s = Student ()

>>> fromtypes Import Methodtype

>>> s.set_age= Methodtype (set_age, s) # Add method to instance s Set_age

>>> S.set_age (24)

>>> S.age

24

>>> S1 = Student ()

>>> S1.set_age-- Note that other instances cannot be called

Traceback (most recent):

File "<stdin>", line 1, in <module>

Attributeerror: ' Student ' object has Noattribute ' Set_age '

binding methods to classes - methods for dynamically increasing classes

>>> Defset_score (self, score):

... self.score = Score

...

>>>student.set_score = Set_score

>>> S.set_score (98)

>>> S.score

98

>>> S1.set_score (100)

>>> S1.score

100

1.1.2   Use__slots__

The action restricts the properties of the instance.

>>> class Student (object):

... __slots__ = (' name ', ' age ') # Restrict property names with tuple

...

>>> s = Student ()

>>> s.name = ' Daidai '

>>> S.name

' Daidai '

>>> S.score = 100

Traceback (most recent):

File "<stdin>", line 1, in <module>

Attributeerror: ' Student ' object has Noattribute ' score '

Note __slots__ only works on the current class instance

>>> class Gstudent (Student):

... pass

...

>>> g = gstudent ()

>>> g.score = 98-- subclasses can still be defined

>>> G.score

98

sub-class plus __slots__ You can restrict the property names of both the parent class and the child class

>>> class Gstudent (Student):

... __slots__ = (' score ', ' Grade ')

... pass

...

>>> g = gstudent ()

>>> g.unslot=898

Traceback (most recent):

File "<stdin>", line 1, in <module>

Attributeerror: ' Gstudent ' object has Noattribute ' Unslot '

>>> g.name = ' Daidai '

>>> G.name

' Daidai '

This article is from the "90SirDB" blog, be sure to keep this source http://90sirdb.blog.51cto.com/8713279/1826207

Python advanced programming for objects--using __slots__