物件導向之反射

isinstance與issubclass是python的內建模組:

# isinstance

class
foo:
pass
class
boo:
pass
foo_obj = foo(
)boo_obj = boo(
)print
(isinstance
(foo_obj, foo)
)# true
print
(isinstance
(boo_obj, foo)
)# false

#issubclass

class
father
:pass
class
sub(father)
:pass
class
foo:
pass
print
(issubclass
(sub,father)
)#true	
print
(issubclass
(foo,father)
)#false

注意: 反射的四個方法是python內建的。

class

foo:
def__init__
(self,x,y)
:        self.x = x
self.y = y
foo_obj = foo(10,
20)#hasattr 通過字串x 判斷物件中是否有 x屬性
print
(hasattr
(foo_obj,
'x')
)#true
print
(hasattr
(foo_obj,
'z')
)#false
#getattr 通過 字串 獲取物件的屬性或方法
print
(getattr
(foo_obj,
'x')
)#10
#若屬性不存在,則返回預設值
res =
getattr
(foo_obj,
'z',
'預設值'
)print
(res)
#預設值
#setattr
# 為foo_obj設定乙個屬性z，值為30
setattr
(foo_obj,
'z',30)
print
(hasattr
(foo_obj,
'z')
)#true
#delattr
delattr
(foo_obj,
'z')
print
(hasattr
(foo_obj,
'z')
)#false

反射應用:

class
filecontrol
:def
run(self)
:while
true
:            user_input =
input()
.strip(
)# 通過使用者輸入的字串判斷方法是否存在，然後呼叫相應的方法
ifhasattr
(self,user_input)
:                func =
getattr
(self,user_input)
func(
)else
:print
('輸入有誤'
)def
upload
(self)
:print
('檔案正在上傳'
)def
download
(self)
:print()
filecontrol_obj = filecontrol(
)filecontrol_obj.run(
)

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