Passing an Python Class Attribute Given a String

Question

Here is a class

Class A:
    def __init__(self, a, b):
        self.a = a
        self.b = b

    def set_value(self,"attribut_String",value):   # passing a attribute in String
        if "attribut_String" = "AAAA":
            self.cal_function("a",value) 
        else "attribut_String" = "BBBB":
            self.cal_function("b",value) 

    def cal_function(self,att,value):
        self.att = value       # process the passing string as attribute object

Now , i'm try to a result like this :

input:rlt = A(a = 1, b = 2)
input:rlt.a
output: 1
input:rlt.set_value("a",3)
input:rlt.a
output:4

May it seems unnecessary because I simplified the scenario . I have to code in this way

have a look at getattr and setattr

Hans Then
– Hans Then

2012-11-14 09:33:29 +00:00
Commented Nov 14, 2012 at 9:33 — Hans Then
– Hans Then, Commented Nov 14, 2012 at 9:33
What not just use rlt.a = 3?

alexvassel
– alexvassel

2012-11-14 09:36:38 +00:00
Commented Nov 14, 2012 at 9:36 — alexvassel
– alexvassel, Commented Nov 14, 2012 at 9:36

alestanis · Accepted Answer · 2012-11-14 09:42:46Z

3

You can use a control flow inside your set_value function:

def set_value(self, member, value):
    if member == "a":
        self.a = value
    elif member == "b":
        self.b = value

If you don't mind dropping the set_value function, you can use the setattr function:

setattr(myobject, "a", value)

or even

def set_value(self, member, value):
    setattr(self, member, value)

You can also use a dictionary:

def set_value(self, member, value):
    members = {
        "a" : self.a,
        "b" : self.b
    }
    members[member] = value

edited Nov 14, 2012 at 9:42

answered Nov 14, 2012 at 9:35

alestanis

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2 Comments

glglgl Over a year ago

what do you do with members in the last step?

Shawn Zhang Over a year ago

hi, Alestanis , that's really classic explanation . but sorry , I didn't make myself clear enough..could you pls check the updated question ?Thanks

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