Get value from string representing local variable

Question

I have a local variable name as a string, and need to get its value.

variable = 22
"variable".to_variable?

How can I get the value 22 form the string?

score 35 · Answer 1 · answered Jun 15 '15 at 08:25

35

binding.local_variable_get("variable")
# => 22

answered Jun 15 '15 at 08:25

sawa

Is there a way to guard against errors if no variable exists with that name? – Chris A Feb 20 '20 at 16:31

score 6 · Accepted Answer · edited May 23 '17 at 10:30

6

You can use eval.

variable = 22
eval("variable")
# => 22

However eval can be nasty. If you dont mind declaring an instance variable, you can do something like this too:

@variable = 22
str = "variable"
instance_variable_get("@#{str}")
# => 22

edited May 23 '17 at 10:30

Community

answered Jun 15 '15 at 08:08

shivam

10

There is no need for `eval` here, just use [`Binding#local_variable_get`](http://ruby-doc.org/core-2.2.2/Binding.html#method-i-local_variable_get). – Jörg W Mittag Jun 15 '15 at 11:07
1

@JörgWMittag I learned about binding just today through [sawa's answer](http://stackoverflow.com/a/30840502/3035830). I knew eval was bad so mentioned that in my answer. But thanks for pointing out.. :) – shivam Jun 15 '15 at 11:11

usmanali · Answer 3 · 2015-06-15T08:31:51.523

1

use eval() method:

variable = 22
eval "variable" #"variable".to_variable?
# => 22

edited Jun 15 '15 at 08:31

answered Jun 15 '15 at 08:08

usmanali

5

There is no need for `eval` here, just use [`Binding#local_variable_get`](http://ruby-doc.org/core-2.2.2/Binding.html#method-i-local_variable_get). – Jörg W Mittag Jun 15 '15 at 11:07

3 Answers3