How do I concatenate a string to a variable declaration in Ruby?

Question

I wonder if it is possible to concatenate a variable value or a string to a new variable value declaration in Ruby.

foo = "something"
#new variable declaration:
var_ + foo = "concat variable name"
p var_foo   # => "concat variable name"

n = 2
position + n = Array.new(3, 1)
p position2    # => [1, 1, 1]`

Thank you very much

In general you can't. There are Binding#local_variable_set//local_variable_set, but this is not exactly what you are looking for. Why do you need it? — Konstantin Strukov
– Konstantin Strukov, Commented Oct 26, 2022 at 13:28
@KonstantinStrukov it's just a doubt to know if it can be done like in other languages like php. I am new in Ruby — Marcelo Alarcon
– Marcelo Alarcon, Commented Oct 26, 2022 at 13:37
You can create instance variables dynamically (i.e. generate the variable name dynamically), and you can use eval, but but both approaches make the code hard to maintain. My feeling is that you have here a XY-problem. Even in PHP, I don't see why you would want to do this for a local variable. — user1934428
– user1934428, Commented Oct 27, 2022 at 7:15

3limin4t0r · Accepted Answer · 2022-10-26 19:43:20Z

2

In such a scenario it's probably better to use a Hash instead.

values = {}
values['foo'] = 'something'
values['var_' + 'foo'] = 'concat variable name'

p values['var_foo'] #=> "concat variable name"

n = 2
values["position#{n}"] = Array.new(3, 1)
p values['position2'] #=> [1, 1, 1]

edited Oct 26, 2022 at 19:43

answered Oct 26, 2022 at 13:17

3limin4t0r

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