patryk_chmura on "i want add shortcode 'URL' with forum syntax.."

hi,
sorry for my bad english.
I read on wordpress codex the correct syntax for add a shortcode, but i have not found solution, maybe you can help me :-)

i want add this codex with this syntax
[url=http://example.com/]text[/url]
know how to add the syntax if I wanted to be this
[url url="http://example.com/"]text[/url]
but I'm looking for a way to use the first, in order to lighten the work of many

i try it

function wp_shortcode_url($attr, $content){
 return '<a href="'.$attr[0].'" class="bbcode-url">'.$content.'</a>'.$content;
};
 add_shortcode( 'url', 'wp_shortcode_url');

but dont work, please, help me :-)

thanks 1000 :-)