The any() and all() methods allow to determine if elements of the collection
pass a boolean test:
- any($fn) will return true if at least one element satisfies $fn
- all($fn) will return true if all elements of the collection satisfy $fn
Those was considered as functions for inclusion in PHP language, but rejected.
The $fn callback parameter must be a callable with one or two arguments,
fn ($value) or fn ($key, $value) and return a boolean.
Any other values than true will be falsy. That allows to cope with legacy
PHP functions returning true when the operation succeeds and an error code
if not, like Memcached::deleteMulti().
The execution of the callbacks stop when the result is definitive and can't
be affected by further values:
- for any($fn), execution stops after the first callback returning true
- for all($fn), execution stops after the first callback returning false
References: