Maybe something like:
```php
if (0 !== $minDepth) {
    $this->minDepthRespected = function ($depth) use ($minDepth) { return $depth >= $minDepth; }; 
}
```
and later on:
```php
public function isMinDepthRespected($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?