Re: RFC - Array Of for PHP 7

On 11/01/2017 11:31 PM, Michael Morris wrote: > Drupal 8 accomplishes this through assert() and a helper class. > > function foo ( array $a ) { > assert( Inspector::assertAllStrings( $a )); > } > > This could be improved by having an collectionof operator similar to the > instanceof operator. > > function ( array $a ) { > assert( $a collectionof string ); > } > > I say "collectionof" because while arrays are the most common traversable > objects, they aren't the only ones. The above approach, combined with the > existing assert structure, can provide the dev time checking of the code > while in under development, and it can be turned off in production. Or it > can be used outside of assert to be checked at all times. > > Since this invokes a new keyword I think that would mean this solution > would be PHP 8. > > Brackets might be used with instance of to notify it to traverse down one > level maybe?? > > function ( array $a ) { > assert( $a instanceof [string] ); > } > > This avoids any BC issues, but it looks odd. Not as odd as \ for a > namespace operation :P But odd. While I normally strongly agree with supporting all traversables, not just arrays, in this case I don't think it works.  The whole point of using a traversable is that you don't have all of the values up front.  If you did... you'd just have an array.  So checking "all values" of a traversable in one point in time is a destructive operation as it runs out the iterator, which if it's an infinite iterator could, erm, be bad. Rather, arrays can/should be checked at once (as above), whereas a traversable should be able to declare that it only returns a given type, and if it ever tries to return a different type then the traversable itself type-errors. --Larry Garfield