为什么下面的代码在循环外给出错误的输出

Question

I have below python code

class Cust: 
    def __init__(self): 
        self.name 

surname=["Lai","Sharma","Max"]
def fetchName(surnames):
    custinst=Cust
    custinst.name="Gaurav"+surnames
    return custinst

finalname=[]
print("###inside loop###")
for i in range(len(surname)):
    finalname.append(fetchName(surname[i]))
    print(finalname[i].name)
print("\n###Outside Loop###\n") 
print (finalname[0].name)
print (finalname[1].name)
print (finalname[2].name)

and below is the output

 ###inside loop###
 GauravLai
 GauravSharma
 GauravMax

 ###Outside Loop###

 GauravMax
 GauravMax
 GauravMax

Issue is why outside loop all the values are coming as last assigned value ie GauravMax

Answer 1

You're modifying the Cust class instance instead of creating a new instance of it every loop:

def fetchName(surnames):
    custinst=Cust
    custinst.name="Gaurav"+surnames
    return custinst

Here Cust is the object that contains the class itself, not an instance of it. You can verify this by doing print(Cust.name) after Inside Loop , which will print GauravMax .

You have to create a new instance by calling the constructor:

def fetchName(surnames):
    custinst=Cust()
    custinst.name="Gaurav"+surnames
    return custinst

Currently, your constructor accesses the name property but it hasn't been set, so it will cause an error. You could just avoid that since it's not doing anything:

def Cust():
    pass

But consider using the parameters of the constructor when instancing the object:

def Cust():
    def __init__(self, name):
        self.name = name

and then pass the name as a parameter:

def fetchName(surnames):
    return Cust("Gaurav"+surnames)