PHP中的动态比较运算符

Question

是否有可能将比较运算符作为变量传递给函数？我正在寻找生产一些便利功能,例如(我知道这不起作用):

function isAnd($var, $value, $operator = '==')
{
    if(isset($var) && $var $operator $value)
        return true;
}

if(isAnd(1, 1, '===')) echo 'worked';

提前致谢.

Answer 1

您还可以使用version_compare()函数,因为您可以传递将用作比较的运算符作为第三个参数.

Answer 2

这个怎么样？

function num_cond ($var1, $op, $var2) {

    switch ($op) {
        case "=":  return $var1 == $var2;
        case "!=": return $var1 != $var2;
        case ">=": return $var1 >= $var2;
        case "<=": return $var1 <= $var2;
        case ">":  return $var1 >  $var2;
        case "<":  return $var1 <  $var2;
    default:       return true;
    }   
}

测试:

$ops = array( "=", "!=", ">=", "<=", ">", "<" );
$v1 = 1; $v2 = 5;

foreach ($ops as $op) {
    if (num_cond($v1, $op, $v2)) echo "True  ($v1 $op $v2)\n"; else echo "False ($v1 $op $v2)\n";
}

Answer 3

小班上怎么样:

class compare
{
  function is($op1,$op2,$c)
  {
     $meth = array('===' => 'type_equal', '<' => 'less_than');
     if($method = $meth[$c]) {
        return $this->$method($op1,$op2);
     }
     return null; // or throw excp.
  }
  function type_equal($op1,$op2)
  {
      return $op1 === $op2;
  }
  function less_than($op1,$op2)
  {
      return $op1 < $op2;
  }
}

Answer 4

最上面的答案推荐一个小班，但我喜欢一个特质。

trait DynamicComparisons{

private $operatorToMethodTranslation = [
    '=='  => 'equal',
    '===' => 'totallyEqual',
    '!='  => 'notEqual',
    '>'   => 'greaterThan',
    '<'   => 'lessThan',
];

protected function is($value_a, $operation, $value_b){

    if($method = $this->operatorToMethodTranslation[$operation]){
        return $this->$method($value_a, $value_b);
    }

    throw new \Exception('Unknown Dynamic Operator.');
}

private function equal($value_a, $value_b){
    return $value_a == $value_b;
}

private function totallyEqual($value_a, $value_b){
    return $value_a === $value_b;
}

private function notEqual($value_a, $value_b){
    return $value_a != $value_b;
}

private function greaterThan($value_a, $value_b){
    return $value_a > $value_b;
}

private function lessThan($value_a, $value_b){
    return $value_a < $value_b;
}

private function greaterThanOrEqual($value_a, $value_b){
    return $value_a >= $value_b;
}

private function lessThanOrEqual($value_a, $value_b){
    return $value_a <= $value_b;
}

}