python-Object-oriented reflection

Reflection

The dynamic assembly is implemented, and the properties and methods in the class are reflected through the string.

Yi, hasarttr (obj,name_str)

Function: Determines whether an object in obj has an attribute or method of the corresponding NAME_STR string.

Class Dog (object):    def __init__ (self, name):        self.name = name    def eat (self, food):        print ('%s is eating% S "% (self.name, food)) d = Dog (" Tom ") d.eat (' Apple ') choice = input (" >>>: "). Strip () print (hasattr (d, Choice))  # If there is a choice string property or method # # output # >>>:name  # Input object exists in obj property # true# >>>:eat  # Input object exists method # True

Second, GetAttr (OBJ,NAME_STR)

Function: Gets the memory address of the corresponding method in the Obj object or the value of the corresponding property according to the string name_str.

Class Dog (object):    def __init__ (self, name):        self.name = name    def eat (self, food):        print ('%s is eating% S "% (self.name, food)) d = Dog (" Tom ") d.eat (' Apple ') choice = input (" >>>: "). Strip () print (GetAttr (d, Choice))    # Get the memory address of the corresponding method in the D object or the value of the corresponding property # >>>:name  # Gets the value of the input object # tom# >>>:eat   # Get the method of the input object # <bound Method Dog.eat of <__main__. Dog Object at 0x000002a4adb732e8>>

Iii. setattr (x, Y, z)

Function: Adds a new property or new method to the Obj object,setattr (x, ' Y ', V) is equivalent to ' x.y = V '.

1. Add a new method to the object

def bulk (self):  # First define a bulk function    print ("%s is yelling ..."% self.name) class Dog (object):    def __init__ (self, Name):        self.name = name    def eat (self, food):        print ('%s is eating%s '% (self.name, food)) d = Dog ("Tom") choice = Input (">>>:"). Strip () SetAttr (d, Choice, bulk)  # input is talk, so it is equivalent to D.talk = bulk# D.talk (d) Direct write Dead, with D.talk (d) , generally not so write Func = GetAttr (d, Choice)  # with GetAttr to get Func (d) # output # >>>:talk# Tom is yelling ...

2. Add a property to the object

Class Dog (object):    def __init__ (self, name):        self.name = name    def eat (self, food):        print ('%s is eating% S "% (self.name, food)) d = Dog (" Tom ") Choice = input (" >>>: "). Strip () SetAttr (d, Choice, ' Apple ')  # Food, So it's equivalent to D.food = ' Apple ' # print (D.food) so it's dead, or with one of the following print (GetAttr (d, choice)) # output # >>>:food# Apple

Iv. delattr (x, y)

Function: Delete the property or method in the Obj object,delattr (x, ' Y ') is equivalent to ' del x.y ' .

Class Dog (object):    def __init__ (self, name):        self.name = name    def eat (self, food):        print ('%s is eating %s "% (self.name, food)) d = Dog (" Tom ") Choice = input (" >>>: "). Strip () delattr (d, Choice)  # Delete an attribute or method print (d.name) print (d.eat) based on a string

V. Comprehensive use of hasattr, GetAttr, SetAttr

Class Dog (object):    def __init__ (self, name):        self.name = name    def eat (self, food):        print ('%s is eating% S "% (self.name, food)) d = Dog (" Tom ") Choice = input (" >>>: "). Strip () if Hasattr (d, choice):  # Determine the existence of properties and methods in the D object C5/>name_value = GetAttr (d, Choice)  # Get property value    print (name_value)    setattr (d, Choice, "Jerry")  # Modify Property values    Print (GetAttr (d, Choice))  # re-get the value of the property else:    SetAttr (d, Choice, None)  # Sets the value of the property that does not exist    v = GetAttr (d, Choice)    print (v)

python-Object-oriented reflection