Maybe something like:

if (0 !== $minDepth) {
    $this->minDepthRespected = function ($depth) use ($minDepth) { return $depth >= $minDepth; }; 
}

and later on:

public function isMinDepthRespected($depth)
{
    if (!$this->minDepthRespected instanceof \Clousure) {
        return true;
    }

    return call_user_func_array($this->minDepthRespected, array($depth));
}

Or something similar, IMO looks more clear =) What do you think?

It's more readable yes, but it introduces a test inside isMinDepthRespected() method which is called inside a loop and will surely impact performences. Don't you think?

I suggest you to benchmark it. Is the overhead of the instanceof check bigger than the overhead of a function call to return true ?

Do you think a function call itself has a big overhead? I'll perform benchs on this because this pattern is used almost everywhere.

There is some overhead for method calls compared to doing the return directly.

And this overhead becomes much bigger when installing XDebug (which is why there is lots of benchmarks telling array_key_exists is far slower than isset, which is not a function call in PHP)

@stloyd well, you're right, I performed following benchmark https://gist.github.com/jfsimon/33480ec6ade7820bb313 and your solution is better than mine! I update the PR.

And call_user_func is slightly fester than call_user_func_array (~ 115 vs 125).

The second argument to preg_quote() should match the delimiter being used ie ~.

Good catch, thanks!