PHP类的公共变量在反序列化之后是未定义的 - PHP class public variables are undefined after deserialisation

所以在某些时候，ajax调用发送一个JSON，我将其转换为对象并存储在会话中:

    if ( $deps = json_decode( $raw_json, true ) )
    {   
        $pkgs = array();
        foreach ( $deps['vector'] as $key )
        {
            if ( strcasecmp( $key['package'], $key['component'] ) == 0 )
            {
                $package = new Package();
                $package->name = $key['package'];
                $package->version = $key['version'];
                $package->cxx_include = $key['cxx_inc'];
                $package->cxx_link = $key['cxx_link'];
                $pkgs[] = $package;
            }
            else
            {
                foreach( $pkgs as $package ) 
                {
                    if ( $package->name == $key['package'] )
                    {
                        $component = new Component();
                        $component->name = $key['component'];
                        $component->cxx_link = $key['cxx_link'];
                        $package->components[] = $component;
                    }
                }
            }
        }
        $_SESSION['pkgs'] = serialize( $pkgs );

实际的类是:

class Component
{
    public $name;
    public $cxx_link;
}
class Package
{
    public $name;
    public $version;
    public $cxx_inclue;
    public $cxx_link;
    public $components = array();
}

稍后，我对它们进行反序列化并尝试解析:

    $pkgs = isset( $_SESSION['pkgs'] ) ? unserialize($_SESSION['pkgs']) : array();
    foreach ( $pkgs as $package )
    {
        fwrite( $cmake, "find_package(" . $package->name . " " . $package->version . " " );
        if ( count( $package->components ) > 0 )
        {
            fwrite( $cmake, "COMPONENTS " );
            foreach ( $package->components as $component )
                fwrite( $cmake, $component->name. " " );
            fwrite( $cmake, "REQUIRED )'r'n" );
        }
        if ( isset( $package->cxx_include ) )
            // ERROR here: undefined variable
            fwrite( $cmake, "include_directories(${".$package->cxx_include."})'r'n" );
        if ( isset( $package->cxx_link ) )
            // ERROR here: undefined variable
            fwrite( $cmake, "target_link_libraries($rapp_name ${".$package->cxx_link."})'r'n" );
        foreach ( $package->components as $component )
        {
            if ( isset($component->cxx_link) )
                // ERROR here: undefined variable
                fwrite( $cmake, "target_link_libraries($rapp_name ${".$component->cxx_link."})'r'n" );
        }
    }

真正让我困惑的不是未定义变量是$component->cxx_link或$package->cxx_link，而是我看到的是JSON中的实际值。

例如:

{
    "vector": [
        {
            "package": "Boost",
            "version": "1.54",
            "component": "Boost",
            "cxx_inc": "Boost_INCLUDE_DIRS",
            "cxx_link": "Boost_LIBRARIES"
        },
        {
            "package": "Boost",
            "version": "1.54",
            "component": "date_time",
            "cxx_inc": "",
            "cxx_link": "Boost_DATE_TIME_LIBRARY"
        },
        {
            "package": "Boost",
            "version": "1.54",
            "component": "filesystem",
            "cxx_inc": "",
            "cxx_link": "Boost_FILESYSTEM_LIBRARY"
        },
        {
            "package": "Opencv",
            "version": "3.0",
            "component": "OpenCV",
            "cxx_inc": "OpenCV_INCLUDE_DIRS",
            "cxx_link": "OpenCV_LIBS"
        },
        {
            "package": "Eigen3",
            "version": "3.0",
            "component": "Eigen3",
            "cxx_inc": "EIGEN3_INCLUDE_DIR",
            "cxx_link": ""
        }
    ]
}

我得到如下错误:

PHP Notice:  Undefined variable: .Boost_INCLUDE_DIRS.
PHP Notice:  Undefined variable: .Boost_LIBRARIES.
PHP Notice:  Undefined variable: .OpenCV_INCLUDE_DIRS.

是我设置类成员的值。如果我正确地理解了这一点，在JSON迭代期间的赋值操作，是否有某种浅复制?

EDIT根据Barmar的注释，我删除了序列化/反序列化，并移动了使用这些类的每个文件顶部的类定义。我不再得到自动加载错误，但我仍然得到完全相同的未定义变量错误

更正:

所以问题是你使用双引号而不是单引号作为字符串。PHP有一种叫做可变变量的东西，您会无意中使用它(参见http://php.net/manual/en/language.variables.variable.php)。

将每个包含类似"${something}"的字符串转换为单引号(或转义Alex提到的美元符号)，您将会很好，即:

fwrite( $cmake, "include_directories(${".$package->cxx_include."})'r'n" );

将

fwrite( $cmake, 'include_directories(${'.$package->cxx_include.'})'."'r'n" );

(注意不能在单引号字符串中使用'r或'n)

老答:

你的Package课有个错别字。

您将其分配给$package->cxx_include，但实际名称缺少"d"。

class Package
{
    public $name;
    public $version;
    public $cxx_inclue; // typo
    public $cxx_link;
    public $components = array();
}