Export trait

index.php

<?php

trait export
{
    public static function getHeader()
    {
        $sCsv = '';
        foreach(get_class_vars(self::class) as $key => $value) {
            $sCsv .= $key . ',';
        }
        $sCsv = trim($sCsv, ',') . "\n";
        
        return $sCsv;
    }
    
    public function toCsv()
    {
        $sCsv = '';
        foreach($this as $key => $value) {
            $sCsv .= $value . ',';
        }
        $sCsv = trim($sCsv, ',') . "\n";
        
        return $sCsv;
    }
}

class U {
    use export;
    
    public $name;
    public $lastName;
    
    public function __construct($name, $lastName) {
        $this->name = $name;
        $this->lastName = $lastName;
    }
}


$csv = U::getHeader();
foreach ([new U("a", "b"), new U("c", "d"), new U("e", "f")] as $u) {
    $csv .= $u->toCsv();
}

echo $csv;
/*
name,lastName
a,b
c,d
e,f
*/