PHP Variables for if statements - php

Question

Ok, I am wanting to do something like this:
$which = !empty($param_id) ? "['groups'][$param_id]" : "['groups']";
And than I'd like it to be able to do something like so...
$all_groups . $which = array(
-1 => array(
'id' => '-1',
'name' => $txt['parent_guests_only'],
'checked' => in_array('-1', $checked) || in_array('-3', $checked),
'is_post_group' => false,
)
And I need it to build an array like so, if !empty($param_id)
$all_groups['groups'][$param_id] = array(the array info);
But if $param_id is empty it should do the this instead:
$all_groups['groups'] = array(the array info);
I don't think I can concatenate it or can I?
Can someone please help me here? This is happening many many times throughout a function, so I don't want to use if... else... statements every single time. Would be too many, thinking of a 1 fast approach for all of them.
Thanks :)
EDIT, here is the function in question:
function ListGroups($checked = array(), $unallowed = array(), $order = array(), $param_id = 0)
{
global $context, $smcFunc, $txt;
// We'll need this for loading up the names of each group.
if (!loadLanguage('ManageBoards'))
loadLanguage('ManageBoards');
if (empty($checked))
return array();
$all_groups['groups'][$param_id] = array();
if (!in_array('-1', $unallowed))
// Guests
$all_groups['groups'][$param_id] = array(
-1 => array(
'id' => '-1',
'name' => $txt['parent_guests_only'],
'checked' => in_array('-1', $checked) || in_array('-3', $checked),
'is_post_group' => false,
)
);
if (!in_array('0', $unallowed))
{
// Regular Members
if (!empty($all_groups['groups']))
$all_groups['groups'][$param_id] += array(
0 => array(
'id' => '0',
'name' => $txt['parent_members_only'],
'checked' => in_array('0', $checked) || in_array('-3', $checked),
'is_post_group' => false,
)
);
else
$all_groups['groups'][$param_id] = array(
0 => array(
'id' => '0',
'name' => $txt['parent_members_only'],
'checked' => in_array('0', $checked) || in_array('-3', $checked),
'is_post_group' => false,
)
);
}
// Load membergroups.
$request = $smcFunc['db_query']('', '
SELECT group_name, id_group, min_posts
FROM {db_prefix}membergroups
WHERE id_group > {int:is_zero}',
array(
'is_zero' => 0,
)
);
while ($row = $smcFunc['db_fetch_assoc']($request))
{
if (!in_array($row['id_group'], $unallowed))
{
$all_groups['groups'][(int) $param_id][(int) $row['id_group']] = array(
'id' => $row['id_group'],
'name' => trim($row['group_name']),
'checked' => in_array($row['id_group'], $checked) || in_array('-3', $checked),
'is_post_group' => $row['min_posts'] != -1,
);
}
}
$smcFunc['db_free_result']($request);
// Let's sort these arrays accordingly!
if (!empty($order))
{
$all_groups['groups'][$param_id] = sortGroups($all_groups['groups'][$param_id], $order);
$context['group_order' . $param_id] = implode(', ', $order);
}
else
{
$context['group_order' . $param_id] = '';
sort($all_groups['groups'][$param_id]);
$x = 0;
foreach ($all_groups['groups'][$param_id] as $key => $value)
{
$x++;
$context['group_order' . $param_id] .= $x < count($all_groups['groups'][$param_id]) ? $value['id'] . ', ' : $value['id'];
}
}
return $all_groups['groups'][$param_id];
}
I need to do a check for !empty($param_id), if so, it needs to build the $all_groups['groups'] array without the $param_id.
So will need to add in a check for if (!empty($params_id)) build the array like so: $all_groups['groups'][$params_id] else build it like this instead: $all_groups['groups']. I don't want a bunch of if... else... statements in here, just a 1 or 5 liner would be GREAT!
Thanks Guys :)

Answer 1

Don't overcomplicate it. :)
$array = array(
/* contents */
);
if (!empty($param_id)) {
$all_groups['groups'][$param_id] = $array;
} else {
$all_groups['groups'] = $array;
}
I don't know what $all_groups['groups'] looks like before this; if it was empty, I'd shorten this to:
$all_groups['groups'] = array(
/* contents */
);
if (!empty($param_id)) {
$all_groups['groups'] = array($param_id => $all_groups['groups']);
}

Answer 2

if (!empty($param_id)) {
$which = &$all_groups['groups'][$param_id]
} else {
$which = &$all_groups['groups'];
}
$which = array(
-1 => array(
'id' => '-1',
'name' => $txt['parent_guests_only'],
'checked' => in_array('-1', $checked) || in_array('-3', $checked),
'is_post_group' => false,
);
unset($which); // unset $which, if you want to use this variable
// in this scope once again

Answer 3

Generally speaking, references are the solution. See #zerkms' answer.
However, if at all possible, I would try to redesign your data structures such that you don't have to resort to this type of conditional behavior. For example, using default as the default missing key:
$which = !empty($param_id) ? $param_id : 'default';
$all_groups['groups'][$which] = array( ... );
I don't know if it's possible in your case, but this could be easier to manage.
Other potential solutions:
$tmp = array( ... );
if ($cond)
$foo = $tmp;
else
$bar = $tmp;
or:
function make_array( ... )
{
return array( ... );
}
if ($cond)
$foo = make_array( ... );
else
$bar = make_array( ... );