How to use a function inside string?

Question

'<a rel="nofollow" href="$1" class="bbc_link new_win" target="_blank">'

I would like use the urlencode() function:

 '<a rel="nofollow" href="urlencode($1)" class="bbc_link new_win" target="_blank">'

... but I can't use this:

 '<a rel="nofollow" href="'.urlencode($1).'" class="bbc_link new_win" target="_blank">'

... because $1 is not a variable in the string; it is instead a meta-variable in a simple free forum.

it send http://www.test.com/out.php?out=http://www.example.com

Oliver O'Neill · Accepted Answer · 2010-12-16 00:58:54Z

6

how about this crazy hack?

<?
$_ = 'urlencode';
echo "<a rel=\"nofollow\" href=\"{$_($1)}\" class=\"bbc_link new_win\" target=\"_blank\">";

answered Dec 16, 2010 at 0:58

Oliver O'Neill

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Danijel · Accepted Answer · 2013-05-16 14:58:29Z

5

Check out this trick:

function foo() { return "title"; }

$func = function($param) { return $param; };

$link = 'http://www.test.com/out.php?out=http://www.example.com';
echo "<a rel=\"nofollow\" href=\"{$func(urlencode($link))}\" class=\"bbc_link new_win\" target=\"_blank\">{$func(foo())}</a>";

$func() will be called as a function, and the expression in the parentheses will be evaluated as any other PHP code.

hack is found here

answered May 16, 2013 at 14:58

Danijel

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1 Comment

starfry Over a year ago

Nice one, however the link is dead. It would be nice to see a workable reference to this trick. That said, it does appear to work; this should be the accepted answer.

Oliver A. · Accepted Answer · 2010-12-15 09:57:05Z

3

There is a way to do this, but take my advice and do not use it. you should not use function calls inside strings. However I´ll post an example just to show what PHP is capable of.

BUT THIS IS AN EXTREME SAMPLE OF BAD PROGRAMMING!!!!

<?php
class FunctionAgent{
    public function __call($name,$args){
        switch (count($args)){
            case 0:
                return  $name();
                break;
            case 1:
                return  $name($args[0]);
                break;
            case 2:
                return  $name($args[0],$args[1]);
                break;  
            case 3:
                return  $name($args[0],$args[1],$args[2]);
                break;
            case 4:
                return  $name($args[0],$args[1],$args[2],$args[3]);
                break;
            case 5:
                return  $name($args[0],$args[1],$args[2],$args[3],$args[4]);
                break;
        }
    }   
}

$_ = new  FunctionAgent();
echo "the current date is {$_->date("y-m-d")}";

?>

answered Dec 15, 2010 at 9:57

Oliver A.

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2 Comments

Stephen M. Harris Over a year ago

Your warning echoes my intuition. But the only problem with this I can actually explicate is that it's unfamiliar convention. Classes/objects are indeed bad practice -- in an OOP context. If FunctionAgent makes a dev's life easier (and every millisecond of script execution time isn't a concern), why not use it?

Oliver A. Over a year ago

@smhmic My golden rule is: stick to what people expect or document it verbosly. It is very interesting how rare you brake the "rules" if you have to write a in depth explanation what you are doing, why you ae doing it and which "cleaner" approaches youconsidered and dismissed. But looking at this 3 year old code I realize I should use call_user_func

Dan Grossman · Accepted Answer · 2010-12-15 06:19:07Z

2

You can't do this. You need to encode the value where it's generated or where it's replaced in this string, not in this template where you don't have access to it.

answered Dec 15, 2010 at 6:19

Dan Grossman

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Comments

Asaph · Accepted Answer · 2010-12-15 06:31:50Z

2

I've just reviewed the string parsing section of the PHP manual and there doesn't appear to be a way of calling a function from within a quoted string (except for dynamically assigning a variable name). Sorry.

edited Dec 15, 2010 at 6:31

answered Dec 15, 2010 at 6:24

Asaph

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Comments

staticsan · Accepted Answer · 2010-12-15 06:25:35Z

0

You need to extend how your templating engine works in order to support this. There's no way to make PHP do it for you.

answered Dec 15, 2010 at 6:25

staticsan

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