How to turn a string into an attribute?

Question

I'm trying to make a really simple command-based python script, and get commands from the terminal's input, but it's not detecting the value of the variable... I'm not good at explaining, so here's my code:

a = 0
b = 0

class commands:
    def add():
        a = int(input("first number "))
        b = int(input("second number "))
        print(a + b)

commander = commands
cmd = input("what command ")
commander.cmd()

When I run it, it gives me an error saying Exception has occurred: AttributeError type object 'commands' has no attribute 'cmd' I'm still relatively new to Python, so sorry if it's something really obvious. Thank you, and any help is appreciated.

To create an instance of your `commands` class, you need to call it by using `commander = commands()` (note the parentheses at the end). It's also unclear how you expect the instance to have a `cmd` (or any other) attributes at all. What strings should be turned into attributes? — martineau, Jun 30 '19 at 02:31

score 5 · Accepted Answer · answered Jun 30 '19 at 01:32

5

you just have to do:

getattr(commander, cmd)()

answered Jun 30 '19 at 01:32

developer_hatch

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score 0 · Answer 2 · answered Jun 30 '19 at 09:36

I have modified your code with if-else so that you can get your desired result:-

a = 0
b = 0

class commands:
    def add(self):
        a = int(input("first number "))
        b = int(input("second number "))
        print(a + b)

commander = commands()
cmd = input("what command ")
print(cmd)
if cmd == 'add':
   commander.add()

I hope it may help you.

How to turn a string into an attribute?

2 Answers2