Re: Introducing "Array Of" RFC

On Thu, Jan 16, 2014 at 5:44 PM, Robert Stoll <php@tutteli.ch> wrote: >> How is type checking a bad design? >> >> Between: >> >> function (array $foos) { >> foreach ($foos as $foo) { >> if (! $foo instanceof Foo) { >> throw new InvalidArgumentException("..."); >> } >> $foo->bar(); >> } >> } >> >> and: >> >> function (array $foos) { >> foreach ($foos as $foo) { >> $foo->bar(); // BOOM, fatal error if not correct object given >> } >> } >> >> which one is worse? > > You got me wrong, I don't think that type checking as such is bad but type checking in the > way the RFC promotes it is bad design IMO. If I expect an array with members of a certain type > (regardless if including null or not) then I would not write any of the above code because this is > exactly the bad design I was writing about. > Wouldn't you agree with me that it would be better to type check the entries when they are > added rather than during each function call? > Imagine function foo(Foo[] $foos){} which calls bar and baz which in turn call several other > functions which all have the same type hint Foo[]. > The result would be that you have increased your runtime complexity by the factor of function > calls. That's really ugly and I don't think that the language itself should promote such > bad design. If you go further and support multi-dimensional arrays the same way then you would add a > complexity of n*m for each function call with such a type hint. I'm absolutely +1 with such a statement. > > However, I like the basic idea of the RFC, namely typed arrays. I think a better implementation > would be to introduce that an array holds (visible only internally - could be exposed to userland > later) the defined type and performs the necessary checks during addition and therefore the runtime > complexity for the type hint checks would no longer be linear but constant. Yet, it is probably > better to introduce another internal data structure for this purpose in order that the type hint > "array" does not suffer from the additional checks. > An alternative approach, without changing the language, would be to provide an additional SPL > data structure instead which performs the type check during the addition of an entry. Yes, yes and yes again. +1 This RFC shows that we lack "array of" as a whole structure in PHP, like Java has Vectors. We already talked about this in the past. I'm in favor of designing a new "typed array" structure , instead of adding a new syntax that checks things at runtime of every function call, mainly by iterating over the array at runtime. I dont think we can accept such a penalty, particulary in the case of nested function calls with the same signature, all requiring the engine to iterate for type checking. Julien.P