Re: Re: Improving PHP's type system

On 4/14/2016 8:59 PM, Stanislav Malyshev wrote: > Hi! > >> I don't know what is complicated about "string|Stringable" or >> "Foo|Bar" >> since it is super self-explanatory. However, I find myself checking the > > It may be self-explanatory for you. It's much less self-explanatory for > somebody just starting to learn. It is also very dangerous - if it's > either Foo or Bar, can you call Foo::stuff on it or not? If it's string > or not string, can you call strlen on it? Etc., etc. It adds a lot of > cognitive load and complicates the whole picture. You may have a > specific use case where it is useful (which we have yet to see btw) but > please remember it's a language with literally millions of use cases and > users. > Reduce assertions*, enhance self-documentation, making code more robust, perform checks in the VM and not in userland, ... function fn($arg) { assert('is_string($arg) || method_exists($arg, "__toString")'); } interface Stringable { function __toString(): string; } function fn(string|Stringable $arg) { // :) } You can find more information on the topic here: https://en.wikipedia.org/wiki/Tagged_union * Assertions in PHP are very error prone if combined with refactoring due to the fact that one should enclose the actual assertion in a string. -- Richard "Fleshgrinder" Fussenegger

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