Get value if set, or default

Hi,

The function Robert proposes only works for going one key deep.

That means one would have to specify getd($arr['sublevel'],$subkey),
which would then create the key 'sublevel'.
(That is assuming one has access to the parent keys)

I have addressed this in the following function:

function arr_getd(&$space,$path,$default=""){
if (is_array($space) ):
if (array_key_exists($path,$space) ):
return $space[$path];
endif;
if($path{0}=="$"):
$path=substr($path,1);
endif;
if(strpos($path,"]")>0):
$tmp_pos = strpos($path,"[");
if ($tmp_pos>0):
// rep arr x[.]
$path = '["'.substr($path,0,$tmp_pos).'"]'.substr($path,$tmp_pos);
endif;
return eval("return (isset($space$path))?$space$path:$default;");
endif;
endif;
return $default;
}

Now, I can pass in a string representation like this:

$val = arr_getd($arr,"['sublevel']['$subkey']","default");

This allows me to control at what point the reference autovivifies the
passed-in array space.

Unfortunately, this approach requires the use of eval in order to
access the isset() function. Coupled with the logic and string
functions, it takes a significant performance hit.

Since I use this inside loops, I would very much appreciate a
language-level implementation similar to isset(), which doesn't require
that a variable be passed in as a string representation.

Is such a thing is acceptable to the majority?

Guy N. Hurst

Robert Cummings wrote:

Why not augment the userland function to the following:

function getd( &$sourceArray, $key, $default=null )
{
if( isset( $sourceArray[$key] ) )
{
return $sourceArray[$key];
}

return $default;

}

Cheers,
Rob.

It's rare to find functionality that cannot be effectively implemented
in userland PHP code, but this appears to be one of them.

The issue here is the capability to check if an array index (or
variable) is set, if so, return its value, or return a passed in default
value. This can be accomplished using if statements or the ternary
operator, but they quickly become tiresome for so routine a task.
Especially when dealing with nested associative arrays, for example:

$myVar =
(isset($_SESSION['application']['section']['page']['title']))?$_SESSION[
'application']['section']['page']['title']:"Default Title";

Wouldn't this be better:

$myVar =
getd($_SESSION['application']['section']['page']['title'],"Default
Title");

At first glance defining a function that will accomplish this appears
easy:

function getd($var,$default='')
{
if(isset($var))
return $var;
else
return $default;
}

$myVar = getd($arr['noindex']);

But this is not notice level compliant, producing an error if the index
doesn't already exist.

Re-writing the function to pass by reference seems to fix this at first
glance:

function getd(&$var,$default='')
{
. . .
}

$myVar = getd($arr['noindex']);

It no longer gives a notice. But the call mentioned above will now
create the index mentioned, setting its value to null, which, while not
necessarily wrong, still means that a foreach iteration or array_keys()
call will show that the key now exists. (though isset() will not.)

Since writing a userland function to accomplish this seems impossible
while maintaining notice-level compliance, could this be accomplished at
the language level? Perhaps by adding a statement similar to isset? It
would seem a very helpful addition to PHP and would not need to affect
other language constructs.

--
Guy Hurst
Senior Developer
Web Teks, Inc.
http://www.webteks.com
Phone: 757.578.4923
Toll free: 877.Web.Teks
Fax: 757.578.4996