Using string as variable name

Question

Hola,

Is there any way for me to use a string to call a method of a class? Here's an example that will hopefully explain better (using the way I think it should be)

class helloworld():
    def world(self):
        print "Hello World!"

str = "world"
hello = helloworld()

hello.`str`()

Which would output hello world.

Thanks in advance.

Answer 1

You can use getattr:

>>> class helloworld:
...     def world(self):
...         print("Hello World!")
... 
>>> m = "world"
>>> hello = helloworld()
>>> getattr(hello, m)()
Hello World!

• Note that the parens in class helloworld() as in your example are unnecessary, in this case.
• And, as SilentGhost points out, str is an unfortunate name for a variable.

Answer 2

one way is you can set variables to be equal to functions just like data

def thing1():
    print "stuff"

def thing2():
    print "other stuff"

avariable = thing1
avariable ()
avariable = thing2
avariable ()

And the output you'l get is

stuff
other stuff

Then you can get more complicated and have

somedictionary["world"] = world
somedictionary["anotherfunction"] = anotherfunction

and so on. If you want to automatically compile a modules methods into the dictionary use dir()

Answer 3

Warning: exec is a dangerous function to use, study it before using it

You can also use the built-in function "exec":

>>> def foo(): print('foo was called');
...
>>> some_string = 'foo';
>>> exec(some_string + '()');
foo was called
>>>

Answer 4

What you're looking for is exec

class helloworld():
    def world(self):
        print "Hello World!"

str = "world"
hello = helloworld()

completeString = "hello.%s()" % str

exec(completString)