Here is a simple example, using class:
$input = array(
'element1' => 'value1',
'element2' => 'value2',
'element3' => 'value3'
);
echo FlatData::flatArray($input,', ', '=');
class FlatData
{
public static function flatArray(array $input = array(), $separator_elements = ', ', $separator = ': ')
{
$output = implode($separator_elements, array_map(
function ($v, $k, $s) {
return sprintf("%s{$s}%s", $k, $v);
},
$input,
array_keys($input),
array_fill(0, count($input), $separator)
));
return $output;
}
}