I was thinking of removing/hiding admin-bar from my wordpress (3.1.1) installation.

I visited following link:


I was surprised to see only a single line to remove/hide admin-bar

add_filter( 'show_admin_bar', '__return_false' );

My question is what is __return_false means? why __ and _?

1 Answer 1


WordPress contains built in functions for quickly returning values.

They are intended to be used as a quick built in function that returns a common value to a filter hook such as true, false, or an empty array.

  • __return_false — Returns the Boolean value of false.
  • __return_true — Returns the Boolean value of true.
  • __return_empty_array — Returns an empty PHP array.
  • __return_zero — Returns the integer 0.
  • __return_null — Returns NULL.
  • __return_empty_string — Returns ''.
  • I cannot see a meaningful reason for these constants.
    – Lovor
    Feb 3, 2021 at 14:14
  • 1
    They aren't constant, they're actual functions. This saves you from having to code something like function justToReturnFalse() { return false; }
    – SeBsZ
    Mar 10, 2021 at 8:58
  • 2
    they are mostly useful in writing short anonymous function attached to filters, like \add_filter( 'woocommerce_email_enabled_new_order, '__return_false' );
    – Q Studio
    Dec 13, 2021 at 22:06

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