Question: Just to help other developers, because there is no similar question on SO. 

```
div class=(is_active? ? 'active' : 'inactive')
div class=('active' if is_active?)

```

Answer: 
See the examples below: 

```
div class=(is_active? ? 'active' : 'inactive')
div class=('active' if is_active?)

```

The same approach can be used to assign dynamic values to other attributes.
If you have multiple conditions I am doing right now something like

```
div class=(('foo ' if is_foo?) + ('bar' if is_bar?))

```

Though I feel it to be a blemish if is\_bar? return false and the generated HTML results in

```
<div class="foo "></div>

```

(the blemish is the blank character after the `foo`). If someone had a solution for that would be awesome.