CODEWITHSUNDEEP
python-3.x
Brett McGruddy
Brett McGruddy

Reputation: 23

dynamically create/call variables in python3

Hello everyone is there a better way to dynamically create/call variables, I'm trying to create a structural parser that will read the object data in a block and create those objects as variables dynamically as they are discovered.

This is and example of my current method, but it feels like I'm going about this wrong.

>>> VAR="VAR2"
>>> class item():
...     pass
... 
>>> newitem=item()
>>> exec('newitem.'+VAR+'=\''+'hello'+'\'')
>>> newitem.VAR2
'hello'
>>>

Upvotes: 2

Views: 4256

Answers (2)

kelloti
kelloti

Reputation: 8951

I think you're on the right track for dynamically creating variables, although I would question why you're not using a hashmap. Why not do

newitem = {}
newitem[VAR] = 'hello'

Try to stay away from the eval statement as much as possible because you have to adjust for "python injection". i.e. VAR could include a "'" which might cause invalid code. It's much easier to just use regular Python constructs when possible

Upvotes: 4

Paul Fisher
Paul Fisher

Reputation: 9666

Use setattr.

setattr(object, attribute_name, value)

So, for example, setattr(a, "pancakes", "syrup") is (more or less) the same as a.pancakes = "syrup"

So, you can use setattr(newitem, VAR, "hello") to make newitem.VAR2 become "hello".

Upvotes: 4

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