# Callback - `v::callback(callable $callback)` This is a wildcard validator, it uses a function name, method or closure to validate something: ```php v::callback('is_int')->validate(10); // true ``` (Please note that this is a sample, the `v::intVal()` validator is much better). As in `v::call()`, you can pass a method or closure to it. *** See also: * [Call](Call.md) * [CallableType](CallableType.md) * [FilterVar](FilterVar.md)