Description:
------------
Not sure how open you are to feature requests like this. 
I use my own function bsprintf() (i.e. boolean sprintf) 
quite a bit for display code. What it does is return 
$var outputted according to $format *only* if $var is 
not empty, otherwise return nothing. If (optional) 
$default is passed in, $default is returned instead of 
nothing if $var is empty.

function bsprintf($var,$format='%s',$default="") {
if (!empty($var)) {return sprintf($format,$var);}
else if (!empty($default)) return $default;
};

Thought I'd suggest implementing something like this as 
a built-in function. Here is a brief example of the type 
of use that I've found useful, mostly to keep code 
simple, condensed, and readable (especially with long 
scripts):


---- USING bsprintf -----

	$apples=100;
	echo "% Apples: ".bsprintf($apples,'%s%%',"None.")." 
/ % Oranges: ".bsprintf($oranges,'%s%%',"None.");

(Total lines: 2)
Returns: % Apples: 100% / % Oranges: None.


---- NOT USING bsprintf -----

	$apples=100;
	echo "% Apples: ";
	echo (!empty($apples)) ? $apples."%" : "None.";
	echo " / % Oranges: ";
	echo (!empty($oranges)) ? $oranges."%" : "None.";

	(OR)

	$apples=100;
	echo "% Apples: ".((!empty($apples)) ? $apples."%" : 
"None.")." / % Oranges: ".((!empty($oranges)) ? 
$oranges."%" : "None.");

(Total lines: 5, or 2-- including a really ugly, hard to 
read one)
Returns: same as above!