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Message-ID: <44584619.60400@lorenso.com>
Date: Wed, 03 May 2006 00:56:41 -0500
Reply-To: dante@lorenso.com
Organization: LarkSpark Corporation
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Subject: Seeking 'coalesce' php internal function
From: dante@lorenso.com ("D. Dante Lorenso")

All,

I'm sure this has been asked somewhere, but since I see requests for 
features for 5.2 or 6.0, I'd like to add a "simple" item to the list 
which would be quite useful to me and would simplify and clean up a lot 
of code out there:

    function coalesce(...)

This works much like in the SQL version of the same.  In SQL, the 
function returns the first non-null argument from an arbitrary list.  In 
our use, it should return the first non-empty value from the list:

Example:

    $x = "dante";
    $y = "";
    $z = "";

    $value = coalesce($z, $y, $x); // $value = "dante"

This function would ideally be built into the language and bypass 
warnings about undefined variables like 'empty' does.  It might be nice 
to have several varieties of this function:

    * return first parameter where empty() is FALSE
    * return first parameter where isset() is TRUE

I don't think something like this can NOT be written in userspace 
because the 'isset' and 'empty' checks need to be run before arguments 
can be passed to a user function or warnings will start flying.  A 
function like this simplifies code which used to look like this:

    if (!empty($_POST["postkey"])) {
        $value = $_POST["postkey"];
    }
    elseif (!empty($_GET["getkey"])) {
        $value = $_POST["getkey"];
    }
    elseif (!empty($default_value)) {
        $value = $default_value;
    }
    else {
        $value = "hard coded value";
    }

Into this:

    $value = coalesce($_POST["postkey"], $_GET["getkey"], 
$default_value, "hard coded value");

Can this be built and included?

Dante