PHP RFC: is_countable


In PHP 7.2, a Warning was added while trying to count uncountable things. After that, everyone was forced to search and change their code, to avoid it. Usually, the following piece of code became standard:

if (is_array($foo) || $foo instanceof Countable) {
    // $foo is countable

This condition, to check if a variable “is countable”, is also very common in methods that return the count of the elements:

if (is_array($foo) || $foo instanceof Countable) {
    return count($foo);


This RFC proposes a new type function, that returns true if the given value is an array type or an instance of the Countable interface.


if (is_array($foo) || $foo instanceof Countable) {
    // $foo is countable


if (is_countable($foo)) {
    // $foo is countable



bool is_countable(mixed $var)

Verify that the content of a variable is an array or an object implementing Countable



The value to check

Return Values

Returns TRUE if var is countable, FALSE otherwise


Example #1: is_countable

var_dump(is_countable([1, 2, 3])); // bool(true)
var_dump(is_countable(new ArrayIterator(['foo', 'bar', 'baz']))); // bool(true)
var_dump(is_countable(new ArrayIterator())); // bool(true)
var_dump(is_countable(new stdClass())); // bool(false)

Example #2: is_countable with conditions

$foo = ['', []];
if (is_countable($foo)) {
    var_dump(count($foo)); // int(2)

Backward Incompatible Changes

None, as this is a new function only.

Proposed PHP Version

The next PHP 7.x, current version 7.3.

RFC Impact

This RFC has no impact on SAPIs, existing extensions, Opcache, etc.

Future Scope

Is out of scope, but a new countable type could be cogitated in the future.

Proposed Voting Choices

Since this is not a PHP language changed, a 50% + 1 majority is required.

Proposal and Patch

The patch (including tests) for this proposal is available in GitHub Pull Request #3026.


rfc/is-countable.txt · Last modified: 2018/01/21 21:45 by carusogabriel