eval() does not assign variable at runtime

Question

I use eval() to assign a list to a var:

eval('mylist = [1,2,3]')

but when I run it , I got a SyntaxError. What's wrong with it? If I cannot do assignment in the eval(), how do I assign a var in the runtime.

On a totally unrelated note, you're probably better off using either locals(), globals(), or for the really daring, a dictionary. — AI Generated Response
– AI Generated Response, Commented Jun 21, 2013 at 7:43
@Snakes and Coffee: Now I have learned these two functions. Here is my situation: I want to create a new member var in a class. How do I implement it ? — Fei Xue
– Fei Xue, Commented Jun 21, 2013 at 7:56
@SnakesandCoffee much better, <your object> would be self if this is in __init__ for example — jamylak
– jamylak, Commented Jun 21, 2013 at 8:57

Ashwini Chaudhary · Accepted Answer · 2013-06-21 07:48:53Z

13

Use exec for statements:

>>> exec 'lis = [1,2,3]'
>>> lis
[1, 2, 3]

eval works only on expressions, like 2*2,4+5 etc

eval and exec are okay if the string is coming from a known source, but don't use them if the string is coming from an unknown source(user input).

Read : Be careful with exec and eval in Python

edited Jun 21, 2013 at 7:48

answered Jun 21, 2013 at 7:38

Ashwini Chaudhary

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2 Comments

anon Over a year ago

Not that this is exec('mylist = [1, 2, 3]') in python 3

SethMMorton Over a year ago

Insert obligatory "be careful with exec, it can be dangerous" here

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