Why is Call-Time Pass-by-Reference Deprecated in PHP and How Can I Fix It?

Call-Time Pass-by-Reference Deprecated: Understanding and Resolution

PHP's warning "Call-time pass-by-reference has been deprecated" indicates the outdated usage of the & symbol to pass variables by reference during function calls. This practice has been discouraged for years, and PHP 8 has officially deprecated it.

Causes of the Deprecation:

In older PHP versions, passing variables by reference using the & symbol was necessary to modify objects passed as arguments. However, modern PHP versions natively support passing objects by value but behave as if they were passed by reference. This means that modifying an object within a function also modifies the original object.

Resolution:

To resolve the deprecation warning and ensure code compatibility with future PHP versions, remove the & symbols from the lines of code where variables are passed by reference.

In your provided code, the & symbols can be removed as follows:

function XML() {
    $this->parser = xml_parser_create();
    xml_parser_set_option($this->parser, XML_OPTION_CASE_FOLDING, false);
    xml_set_object($this->parser, $this);
    xml_set_element_handler($this->parser, 'open', 'close');
    xml_set_character_data_handler($this->parser, 'data');
}
function destruct() {
    xml_parser_free($this->parser);
}
function parse($data) {
    $this->document = array();
    $this->stack    = array();
    $this->parent   = &$this->document;
    return xml_parse($this->parser, $data, true) ? $this->document : NULL;
}

Additional Considerations:

• Remove all occurrences of & from variable passing, not just where the warning is generated.
• Pass object variables by value, as PHP natively handles their modification appropriately.
• Update your code to adhere to modern PHP coding standards to avoid similar deprecation warnings in the future.

The above is the detailed content of Why is Call-Time Pass-by-Reference Deprecated in PHP and How Can I Fix It?. For more information, please follow other related articles on the PHP Chinese website!