Add Return Empty String Function

[wpsmith]

There's an easy way to return boolean, integer (0), and an empty array. But what about an empty string?
root\wp-includes\functions.php

/**
 * Returns an empty string.
 *
 * Useful for returning an empty string to filters easily.
 *
 * @since 3.0.0
 * @see __return_empty_string()
 * @return string Empty string
 */
function __return_empty_string() {
	return '';
}

[nacin]

There is also one for null, which could be used in nearly all places __return_empty_string() might be used. Where might one use it, though? I closed #20358.

[wpsmith]

I probably missed it but where is the return null function? I see __return_false but don't see __return_null. If I am not mistaken those are two different ideas/purposes. Likewise, if one wishes to be consistent with types, it would be beneficial to have __return_empty_string and maybe even __return_null (if it doesn't exist already).

[nacin]

__return_null is new in 3.4, I think.

[SergeyBiryukov]

Replying to wpsmith:

I probably missed it but where is the return null function?

It was added in #18845.

[trepmal]

Added a patch since this ticket wasn't closed, just in case...

Using __return_null when I really want an empty string seems hackish.

There are at least 3 plugins in the repo doing their own version of __return_empty_string but 1 returns the parameter passed to it, and another actually echoes an empty string. Not sure if only 3 attempts is an indication that there's not a big enough need, or if that 2 of 3 attempts doing it wrong indicates there should be a core function to save them.

[jtsternberg]

Agreed. Seems hackish. Any word from the powers that be?

[helen]

#24996 was marked as a duplicate.

[DrewAPicture]

+1. Moving to 3.7 for review.

@trepmal: Maybe change the @see tag to __return_null() and update @since to 3.7.0

[trepmal]

with @DrewAPicture's suggestions

[nacin]

In 25037:

Add a function to return an empty string, for filters. props wpsmith, trepmal. fixes #20357.