PHP扩展类

Question

我正在重写我的一些代码以兼容 PHP 7。 虽然我重写的大多数类都可以正常工作，但我遇到了尝试从原始（父）类访问函数的扩展类的问题，并且想知道我做错了什么。

这是主类：

  class tableBlock {
    var $table_border = '0';
    var $table_width = '100%';
    var $table_cellspacing = '0';
    var $table_cellpadding = '2';
    var $table_parameters = '';
    var $table_row_parameters = '';
    var $table_data_parameters = '';

//function tableBlock($contents) { // modified for php 7 compatibility
    function __construct($contents) {
      $tableBox_string = '';

      $form_set = false;
      if (isset($contents['form'])) {
        $tableBox_string .= $contents['form'] . "\n";
        $form_set = true;
        array_shift($contents);
      }

      $tableBox_string .= '<table border="' . $this->table_border . '" width="' . $this->table_width . '" cellspacing="' . $this->table_cellspacing . '" cellpadding="' . $this->table_cellpadding . '"';
      if (tep_not_null($this->table_parameters)) $tableBox_string .= ' ' . $this->table_parameters;
      $tableBox_string .= '>' . "\n";

      for ($i=0, $n=sizeof($contents); $i<$n; $i++) {
        $tableBox_string .= '  <tr';
        if (tep_not_null($this->table_row_parameters)) $tableBox_string .= ' ' . $this->table_row_parameters;
        if (isset($contents[$i]['params']) && tep_not_null($contents[$i]['params'])) $tableBox_string .= ' ' . $contents[$i]['params'];
        $tableBox_string .= '>' . "\n";

        if (isset($contents[$i][0]) && is_array($contents[$i][0])) {
          for ($x=0, $y=sizeof($contents[$i]); $x<$y; $x++) {
            if (isset($contents[$i][$x]['text']) && tep_not_null($contents[$i][$x]['text'])) {
              $tableBox_string .= '    <td';
              if (isset($contents[$i][$x]['align']) && tep_not_null($contents[$i][$x]['align'])) $tableBox_string .= ' align="' . $contents[$i][$x]['align'] . '"';
              if (isset($contents[$i][$x]['params']) && tep_not_null($contents[$i][$x]['params'])) {
                $tableBox_string .= ' ' . $contents[$i][$x]['params'];
              } elseif (tep_not_null($this->table_data_parameters)) {
                $tableBox_string .= ' ' . $this->table_data_parameters;
              }
              $tableBox_string .= '>';
              if (isset($contents[$i][$x]['form']) && tep_not_null($contents[$i][$x]['form'])) $tableBox_string .= $contents[$i][$x]['form'];
              $tableBox_string .= $contents[$i][$x]['text'];
              if (isset($contents[$i][$x]['form']) && tep_not_null($contents[$i][$x]['form'])) $tableBox_string .= '</form>';
              $tableBox_string .= '</td>' . "\n";
            }
          }
        } else {
          $tableBox_string .= '    <td';
          if (isset($contents[$i]['align']) && tep_not_null($contents[$i]['align'])) $tableBox_string .= ' align="' . $contents[$i]['align'] . '"';
          if (isset($contents[$i]['params']) && tep_not_null($contents[$i]['params'])) {
            $tableBox_string .= ' ' . $contents[$i]['params'];
          } elseif (tep_not_null($this->table_data_parameters)) {
            $tableBox_string .= ' ' . $this->table_data_parameters;
          }
          $tableBox_string .= '>' . $contents[$i]['text'] . '</td>' . "\n";
        }

        $tableBox_string .= '  </tr>' . "\n";
      }

      $tableBox_string .= '</table>' . "\n";

      if ($form_set == true) $tableBox_string .= '</form>' . "\n";

      return $tableBox_string;
    }
  }

这是扩展类：

class box extends tableBlock {
//    function box() {  // modified for php 7 compatibility
    function __construct() {
      $this->heading = array();
      $this->contents = array();
    }


function menuBox($heading, $contents) {

    global $menu_dhtml;              // add for dhtml_menu
    if ($menu_dhtml == false ) {     // add for dhtml_menu

      $this->table_data_parameters = 'class="menuBoxHeading"';
      if ($heading[0]['link']) {
        $this->table_data_parameters .= ' onmouseover="this.style.cursor=\'hand\'" onclick="document.location.href=\'' . $heading[0]['link'] . '\'"';
        $heading[0]['text'] = '&nbsp;<a href="' . $heading[0]['link'] . '" class="menuBoxHeadingLink">' . $heading[0]['text'] . '</a>&nbsp;';
      } else {
        $heading[0]['text'] = '&nbsp;' . $heading[0]['text'] . '&nbsp;';
      }
      $this->heading = $this->tableBlock($heading);

      $this->table_data_parameters = 'class="menuBoxContent"';
      $this->contents = $this->tableBlock($contents);
      return $this->heading . $this->contents . $dhtml_contents;
// ## add for dhtml_menu
    } else {
      $selected = substr(strrchr ($heading[0]['link'], '='), 1);
      $dhtml_contents = $contents[0]['text'];
      $change_style = array ('<br>'=>' ','<BR>'=>' ', 'a href='=> 'a class="menuItem" href=','class="menuBoxContentLink"'=>' ');
      $dhtml_contents = strtr($dhtml_contents,$change_style);
      $dhtml_contents = '<div id="'.$selected.'Menu" class="menu" onmouseover="menuMouseover(event)">'. $dhtml_contents . '</div>';
      return $dhtml_contents;
      }
// ## eof add for dhtml_menu
    }
}

如您所见，我将构造函数修改为__construct，但扩展函数在尝试访问$this->contents = $this->tableBlock($heading); 和$this->contents = $this->tableBlock($contents); 时出错

我尝试使用$this->contents = parent::__construct($contents); 和$this->contents = parent::__construct($heading); 修改这些行，但我可能写错了，因为它也不起作用。

非常感谢任何帮助。

Answer 1

__construct 函数用于构造对象，这意味着它可以在内存中创建对象并初始化一些属性（如果需要）。您在扩展课程中正确使用了它。 但是，您不能从构造函数返回值：Returning a value in constructor function of a class

我建议将您的 __construct 函数再次重命名为 createTableBlock 之类的名称，并使用 parent::createTableBlock($arguments) 从您的扩展类中调用此函数。

另外我建议总是调用你的父构造函数（如果有的话）。您可以通过在扩展类的构造函数中调用parent::__construct 来完成此操作。

应 OP 的要求，他的代码被重写：

  class tableBlock {
    var $table_border = '0';
    var $table_width = '100%';
    var $table_cellspacing = '0';
    var $table_cellpadding = '2';
    var $table_parameters = '';
    var $table_row_parameters = '';
    var $table_data_parameters = '';

    function __construct() {
      //empty
    }

    function tableBlock($contents) {
      $tableBox_string = '';

      $form_set = false;
      if (isset($contents['form'])) {
        $tableBox_string .= $contents['form'] . "\n";
        $form_set = true;
        array_shift($contents);
      }

      $tableBox_string .= '<table border="' . $this->table_border . '" width="' . $this->table_width . '" cellspacing="' . $this->table_cellspacing . '" cellpadding="' . $this->table_cellpadding . '"';
      if (tep_not_null($this->table_parameters)) $tableBox_string .= ' ' . $this->table_parameters;
      $tableBox_string .= '>' . "\n";

      for ($i=0, $n=sizeof($contents); $i<$n; $i++) {
        $tableBox_string .= '  <tr';
        if (tep_not_null($this->table_row_parameters)) $tableBox_string .= ' ' . $this->table_row_parameters;
        if (isset($contents[$i]['params']) && tep_not_null($contents[$i]['params'])) $tableBox_string .= ' ' . $contents[$i]['params'];
        $tableBox_string .= '>' . "\n";

        if (isset($contents[$i][0]) && is_array($contents[$i][0])) {
          for ($x=0, $y=sizeof($contents[$i]); $x<$y; $x++) {
            if (isset($contents[$i][$x]['text']) && tep_not_null($contents[$i][$x]['text'])) {
              $tableBox_string .= '    <td';
              if (isset($contents[$i][$x]['align']) && tep_not_null($contents[$i][$x]['align'])) $tableBox_string .= ' align="' . $contents[$i][$x]['align'] . '"';
              if (isset($contents[$i][$x]['params']) && tep_not_null($contents[$i][$x]['params'])) {
                $tableBox_string .= ' ' . $contents[$i][$x]['params'];
              } elseif (tep_not_null($this->table_data_parameters)) {
                $tableBox_string .= ' ' . $this->table_data_parameters;
              }
              $tableBox_string .= '>';
              if (isset($contents[$i][$x]['form']) && tep_not_null($contents[$i][$x]['form'])) $tableBox_string .= $contents[$i][$x]['form'];
              $tableBox_string .= $contents[$i][$x]['text'];
              if (isset($contents[$i][$x]['form']) && tep_not_null($contents[$i][$x]['form'])) $tableBox_string .= '</form>';
              $tableBox_string .= '</td>' . "\n";
            }
          }
        } else {
          $tableBox_string .= '    <td';
          if (isset($contents[$i]['align']) && tep_not_null($contents[$i]['align'])) $tableBox_string .= ' align="' . $contents[$i]['align'] . '"';
          if (isset($contents[$i]['params']) && tep_not_null($contents[$i]['params'])) {
            $tableBox_string .= ' ' . $contents[$i]['params'];
          } elseif (tep_not_null($this->table_data_parameters)) {
            $tableBox_string .= ' ' . $this->table_data_parameters;
          }
          $tableBox_string .= '>' . $contents[$i]['text'] . '</td>' . "\n";
        }

        $tableBox_string .= '  </tr>' . "\n";
      }

      $tableBox_string .= '</table>' . "\n";

      if ($form_set == true) $tableBox_string .= '</form>' . "\n";

      return $tableBox_string;
    }
  }

这是扩展类：

class box extends tableBlock {
    function __construct() {
      parent::__construct(); //calling parent constructor
      $this->heading = array();
      $this->contents = array();
    }


function menuBox($heading, $contents) {
    global $menu_dhtml;              // add for dhtml_menu
    if ($menu_dhtml == false ) {     // add for dhtml_menu

      $this->table_data_parameters = 'class="menuBoxHeading"';
      if ($heading[0]['link']) {
        $this->table_data_parameters .= ' onmouseover="this.style.cursor=\'hand\'" onclick="document.location.href=\'' . $heading[0]['link'] . '\'"';
        $heading[0]['text'] = '&nbsp;<a href="' . $heading[0]['link'] . '" class="menuBoxHeadingLink">' . $heading[0]['text'] . '</a>&nbsp;';
      } else {
        $heading[0]['text'] = '&nbsp;' . $heading[0]['text'] . '&nbsp;';
      }
      $this->heading = $this->tableBlock($heading);

      $this->table_data_parameters = 'class="menuBoxContent"';
      $this->contents = $this->tableBlock($contents);
      return $this->heading . $this->contents . $dhtml_contents;
// ## add for dhtml_menu
    } else {
      $selected = substr(strrchr ($heading[0]['link'], '='), 1);
      $dhtml_contents = $contents[0]['text'];
      $change_style = array ('<br>'=>' ','<BR>'=>' ', 'a href='=> 'a class="menuItem" href=','class="menuBoxContentLink"'=>' ');
      $dhtml_contents = strtr($dhtml_contents,$change_style);
      $dhtml_contents = '<div id="'.$selected.'Menu" class="menu" onmouseover="menuMouseover(event)">'. $dhtml_contents . '</div>';
      return $dhtml_contents;
      }
// ## eof add for dhtml_menu
    }
}

现在用$this->contents = parent::tableBlock($contents);调用父逻辑

Answer 2

__construct 从不返回值，你应该在构造中使用方法而不是返回值。