Config::has should check for key presence

[tomzx]

The current code in AbstractConfig::has is not going to return an expected result if the value in the configuration is null.

    public function has($key)
    {
        return !is_null($this->get($key));
    }

somekey: null

In this particular case, AbstractConfig::has will return false even if it has the key somekey.

[ashnazg]

+1 -- I'm inclined to agree with the rationale here, that the expectation of the contract from has() is to see if the specified key exists, without any particular regard to what its value is set to.

I concede that the docblock currently states "checking if configuration values exist", but I'd argue that Rule of Least Surprise backs up that the most common expectation from reading has($myKey) would be checking for the key's existence, rather than the non-nullness of the key's value.

[ashnazg]

Since this is effectively copying the current body of get(), I'd suggest letting has() prime the cache when the key is found. You can then remove all this similar logic from get(), and just have get() call out to has() to see if it exists. If has() says false, then get() returns $default... if it says TRUE, then get() can return it right out of the cache.

[tomzx]

Agreed. I've also changed a little "side effect" the get method had, namely that it would set in cache the default value if the key didn't exist, which I think should not happen.

[ashnazg]

Ah, good catch... I agree that would be unexpected behavior to me.

[tomzx]

Replaced by PR #72 targeting develop.