`$wpdb` global object should be retrieved via a helper function to help prevent global stomping

[jtsternberg]

As a matter of convenience and even to provide a small amount of resilience to the $wpdb global, it makes sense that we provide a utility to function to return it. This would allow things like:

wpdb()->get_col( wpdb()->prepare() );

etc.

the entirety of the patch looks like:

function wpdb() {
	global $wpdb;
	return $wpdb;
}

[johnjamesjacoby]

I like this. It minimizes the risk of interacting with the $wpdb global object directly.

I've been including methods in classes to do something similar for a while, so a central wrapper in WordPress core would prevent me from redefining those methods for each class that interacts with it.

[paulwilde]

The patch has a typo, by the way. "wbdp".

[jtsternberg]

fix typo in comment

[pento]

I'm not wild about this. It seems like it'd involve a lot of churn in both core (if we're providing this, we should use it), and in plugins, for when their minimum version catches up to this.

The only thing it prevents is clobbering $wpdb, which you're going to notice pretty quickly. It doesn't prevent more subtle errors which are harder to catch. (For example, changing $wpdb->charset.)

Also, is this proposal just for $wpdb, or all of the globals WordPress provides?

[jtsternberg]

It is a proposal for only $wpdb for now. Re: churn vs global stomping, I think the pros outweigh the cons, but ultimately that is not my call. I'd prefer to never call global $anything; in my code again, so something like this starts to get us there.

[jdgrimes]

I realize performance may not be a big concern here, but FWIW, a function call takes over twice the amount of time as declaring a global. We might want to consider just replacing global $wpdb with $wpdb = wpdb(). Less churn, no global, more performant.

[jdgrimes]

Replying to jdgrimes:

I realize performance may not be a big concern here, but FWIW, a function call takes over twice the amount of time as declaring a global. We might want to consider just replacing global $wpdb with $wpdb = wpdb(). Less churn, no global, more performant.

To clarify, what I'm saying is that replacing every single use of the $wpdb variable with a call to a function will reduce performance. Calling the function just once, and using the variable as we already do will be more performant and won't require the code churn.

[jtsternberg]

Along those lines, I'm curious if there are any performance implications to global $wpdb; return $wpdb; vs return $GLOBALS['wpdb'];.

[jdgrimes]

Replying to jtsternberg:

Along those lines, I'm curious if there are any performance implications to global $wpdb; return $wpdb; vs return $GLOBALS['wpdb'];.

return $GLOBALS['wpdb']; is about 15% faster, based on a similar benchmark I ran a while back.

[jtsternberg]

Switch to using $GLOBALS['wpdb']

[ericlewis]

Tangentially related: #32468

[pento]

I still have the reservations I expressed in comment #4. Lots of code churn for only a little extra protection doesn't seem like a good tradeoff.

[pento]

#37639 was marked as a duplicate.

[pcfreak30]

I think what @jdgrimes said is a good compromise for compatibility and performance though.