When using CF7 (Contact Form 7) is there any way to get the placeholder text from a php function?  

I’ve tried using a shortcode to call the php function, but it doesn’t work.  

Here is my test:

function.php code:

```
add_filter( 'wpcf7_form_elements', 'do_shortcode' );
add_shortcode( 'get_placeholder', 'get_placeholder_func' );
function get_placeholder_func () {
    return "Hello world";
}

```

CF7 template:

```
[get_placeholder]
[text the-field placeholder [get_placeholder]]

```

First line works fine and outputs the text returned from the php function.
Second line doesn't work as it only outputs a end-bracket.

I know I can do it by using js/jQuery, but it is a bit messy.  

Can anybody help? Thanks :)