I want to store and retrieve some variables from object. For example in `a` 

```
a = "a"

```

So far I found two possible ways to do it.

* Using `instance_variable_set` and `instance_variable_get`

```
a.instance_variable_set(:@x, 10)
a.instance_variable_get(:@x) # => 10

```
* or just using `instance_eval`

```
a.instance_eval { @y = 5 }
a.instance_eval { @y } # => 5

```

The second approach looks shorter and simpler for me, is there anything wrong with my code if I prefer this one?