PHP anonymous function causes syntax error on some installations

问题

I have the following code:

    $file_check_method_func = function($n) {
        $n = absint($n);
        if(1 !== $n) { $n = 0; }
        return $n;
    };
    $valid['file_check_method'] = array_map($file_check_method_func, $input['file_check_method']);

This works on my PHP 5.3.5 installation but when I run this code on a PHP 5.2.15 installation I get:

Parse error: syntax error, unexpected T_FUNCTION in /home/xxxx/public_html/xxxx/xxxxxxx/wp-content/plugins/wordpress-file-monitor-plus/classes/wpfmp.settings.class.php on line 220

Line 220 being the first line of the above code.

So my question(s), is there something wrongly written in my code that would give this error? If not is it because of a bug or not supported feature in PHP 5.2.15? If yes then how can I write the above code so not to generate the error?

The above code is in a function in a class.

回答1:

Anonymous functions is a feature added in 5.3

For earlier versions, create a named function and refer it by name. Eg.:

function file_check_method_func($n) {
    $n = absint($n);
    if(1 !== $n) { $n = 0; }
    return $n;
}
$valid['file_check_method'] = array_map('file_check_method_func', $input['file_check_method']);

or inside a class:

class Foo {
  protected function file_check_method_func($n) {
    $n = absint($n);
    if(1 !== $n) { $n = 0; }
    return $n;
  }
  function validate($input) {
    $valid = array();
    $valid['file_check_method'] = array_map(array($this, 'file_check_method_func'), $input['file_check_method']);
    return $valid;
  }
}

I would strongly suggest not to rely on create_function.

回答2:

The syntax for anonymous functions in the example can only be used in PHP >= 5.3. Before PHP 5.3, anonymous functions can only be created with create_function().

回答3:

Anonymous functions using this function-syntax has been added 5.3. But you can define anonymous functions using http://www.php.net/manual/en/function.create-function.php

来源：https://stackoverflow.com/questions/6412032/php-anonymous-function-causes-syntax-error-on-some-installations

标签

syntax-error

php

anonymous-function