Subverting Large If Blocks To Do Your Bidding

Posted by jon on October 22, 2008
Interesting Code, Software Engineering

I came across some “interesting” code today at work, and while I can’t share the actual code snippet I can share something similar. This is what I call 1337h4×0r code, because it works by basically subverting the intended use of the control structure.

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if(($ok = $obj->Check1()) !== true) {
} else if(($ok = $obj->Check2()) !== true) {
} else if(($ok = $obj->Check3()) !== true) {
} else if(($ok = $obj->Check4()) !== true) {
} else if(($ok = $obj->Check5()) !== true) {
} else if(($ok = $obj->Check6()) !== true) {
}
 
if($ok === true) {
  //then do some stuff.
}

Upon first looking at it, I wanted to cry because of how unreadable it was, but after some code review I had a basic understanding of what was trying to be accomplished. Quite clever, but here is how I would have achieved the same result, and a bit more down the 1337h4×0r lines.

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$ok = true
$methods = Array("Check1","Check2","Check3",
                 "Check4","Check5","Check6");
foreach($methods as $method_call) {
    $ok = $ok & $obj->{$method_call}();
    if($ok !== true) {
      break;
    }
}
 
if($ok === true) {
   //then do some stuff.
}

Why do I get that feeling that in PHP 6, this will all stop working?

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3 Comments to Subverting Large If Blocks To Do Your Bidding

Colin Dean
October 22, 2008

Neat. I often forget that PHP can do things like that.

Zack Douglas
October 25, 2008

Two things,

1) Did you intend to put a bitwise AND instead of logical AND in this line: 

$ok = $ok & $obj->{$method_call}();

2) I’ve never been a fan of 

$obj->{$method_call}();

, probably because it requires the context of the 

for

loop to understand just what’s happening. Granted, this can shorten long 

if

s, but the fact that PHP can handle 

new $obj_name()

is a little absurd. 

Eval

may seem a bit old-fashioned, but you can’t be more explicit. Other than that, I like your method better; to me, 

break

has always been an underused instruction.

Zack Douglas
October 25, 2008

Wow, I apologize for the horrid formatting of that comment. Dang Wordpress for not being explicit about <pre> and <code>!

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