Using a string variable as a variable name [duplicate]

Question

Possible Duplicate:
How do I do variable variables in Python?

I have a variable with a string assigned to it and I want to define a new variable based on that string.

foo = "bar"
foo = "something else"   

# What I actually want is:

bar = "something else"

No you don't. The reason you have to use exec is because locals() doesn't support modifications. locals() doesn't support modifications because it would make the implementation more complex and slower and is never a good idea — John La Rooy, Jul 19 '12 at 4:04

Ned Batchelder · Answer 1 · 2012-07-19 04:05:05Z

up vote 59 down vote

You will be much happier using a dictionary instead:

my_data = {}
foo = "hello"
my_data[foo] = "goodbye"
assert my_data["hello"] == "goodbye"

answered Jul 19 '12 at 4:05

Ned Batchelder

164k25308456

4

It does not seem to address the question. – dnsmkl Nov 5 '15 at 19:52

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Jack Leow · Answer 2 · 2012-07-19 04:01:42Z

up vote 43 down vote

You can use exec for that:

>>> foo = "bar"
>>> exec(foo + " = 'something else'")
>>> print bar
something else
>>>

answered Jul 19 '12 at 4:01

Jack Leow

13.9k23442

26

+1 because he answered the question (as bad an idea as it may be). – mgalgs Jun 25 '13 at 3:39

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Gustavo Vargas · Answer 3 · 2012-07-19 04:10:16Z

You can use setattr

name= 'varname'
value= 'something'

setattr(self, name, value) #equivalent to: self.varname= 'something'

print self.varname
#will print 'something'

But, since you should inform an object to receive the new variable, I think this only works inside classes.

marked as duplicate by jogojapan, JBernardo, Karl Knechtel, monkut, Jeremy Banks Jul 19 '12 at 19:09