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I have found a bug report(http://bugs.php.net/bug.php?id=24286) about this though I am not sure if it's relevant to my problem and it's very old. This is my code:

class RegExp {
    function name($e){ .... }
    function email($e){ .... }
    function phone($e){ .... }
}    

$regexp = new RegExp();
$final_keys= array("name", "email", "phone");

for($index=0; $index < count($final_keys); $index ++){
    if(!$regexp->$final_keys[$index]($_POST[$final_keys[$index]])){
        $invalid_uri_vars .= $final_keys[$index].",";
    }
    else{
        $uri_vars = "&".$final_keys[$index]."=".$_POST[$final_keys[$index]];
    }
}

What it does is it uses a value from an array as the name of the method to be called. In other words, I am trying to implement a function call using a variable $final_keys[$index] as its name.

*UPDATE: I tried implementing the suggestions below, nothing seems to work. Here's one of my modifications as suggested:

for($key=0; $key < count($final_keys); $key ++){
    if(!$regexp->{$final_keys[$key]}($_POST[$final_keys[$key]])){
        $invalid_uri_vars .= $final_keys[$key].",";
    }
    else{
        $uri_vars = "&".$final_keys[$key]."=".$_POST[$final_keys[$key]];
    }
}

I get the same error as my original code. Another method using call_user_func but I am not sure if did it right:

for($key=0; $key < count($final_keys); $key++){
    if(!call_user_func(array($regexp, $final_keys[$key]), $_POST[$final_keys[$key]])){
        $invalid_uri_vars .= $final_keys[$key].",";
    }
    else{
        $uri_vars = "&".$final_keys[$key]."=".$_POST[$final_keys[$key]];
    }   
}

And I get this error: Warning: call_user_func(Array) [function.call-user-func]: First argument is expected to be a valid callback in /.........testreqmeta.php on line 91

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4
  • What version of PHP are you using? The above code, after fleshing out (example code should be self-contained) doesn't produce the error you have in your title when run under PHP 5.3.2. It's also best to include the error and an indication of which line generates it within the body of a post, so that there's no confusion over what is happening. Commented Nov 14, 2010 at 10:38
  • I am testing the code on a live site--somewhere in the subfolders. The site is hosted on hostgator I think... Commented Nov 14, 2010 at 13:32
  • That doesn't answer my question. If you're not certain which PHP version your host runs, you can use phpversion to find out. In order to fix a problem with code, the problem needs to be reproducible. Right now, it's not. Some crucial information is missing from your question. Also, the second sample (using brackets) loops over $index but uses $key in the loop body. If that's representative of your actual code, you're referring to an undefined variable ($key), which will cause a warning. Commented Nov 15, 2010 at 5:12
  • I am using version 5.3.1. No, $key and $index are the same, sorry for the inconsistencies. Thanks for your help! Commented Nov 16, 2010 at 15:34

3 Answers 3

Reset to default
1

I'm still not getting any errors (other than the undefined $key in the second sample) when trying the sample code, so I can't say for certain what will fix it, but here's an approach that simplifies things and gets rid of the array indexing operation: use a foreach loop rather than a for loop.

$query = array();
foreach ($final_keys as $key) {
    if(!$regexp->$key($_POST[$key])) {
        $invalid_uri_vars[] = $key;
    } else {
        $query[] = "$key={$_POST[$key]}";
    }
}
$uri_vars = implode('&', $query);

I've also replaced the repeated string appends with an array implosion, which should be slightly more performant. It also makes it easier to further process the query string, if necessary, before submitting it. There are better approaches yet, but that's a whole other topic.

NB. RegExp isn't a very good description of what the class does, hence it isn't a very good name. The class may use regular expressions, but it isn't itself a regular expression (which support operations such as "match" and "replace"; RegExp's API has none of these).

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2 Comments

This works pefectly, thanks! Question: What does this line $query[] = "$key={$_POST[$key]}"; do? Particulary the one in double quotes. It will result to something like this $query = array("key" => "value"); right?
No. It creates a string, not an array. The curly brackets are for complex syntax. The empty square brackets are for auto-indexing. To store a key and value in an array, I'd use $query[$key] = $value, not $query = array($key, $value), except in very particular circumstances.
1

Quoting from your link:

ok, here is some workaround on this problem: in case of

<?
class Test {
    var $var = Array('test_function');
    function test_function($echo_var) {
        echo $echo_var;
    }
}

$test_obj = new test;
$test_obj->var[0]('bla');
?>

you can avoid Fatal error in last string using this instead:

<?
$test_obj->{$test_obj->var[0]}('bla');
?>

So then:

if($regexp->{$final_keys[$index]}($_POST[$final_keys[$index]])){
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0

There's a function for what you are trying to achieve call_user_func:

https://www.php.net/manual/en/function.call-user-func.php

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