Re: Arrow function expressions in PHP

Nikita and all, On Thu, Oct 1, 2015 at 10:58 AM, Nikita Nefedov <inefedor@gmail.com> wrote: > On Thu, 01 Oct 2015 15:33:51 +0300, Rowan Collins <rowan.collins@gmail.com> > wrote: > >> That's not how Rasmus expressed it >> [http://marc.info/?l=php-internals&m=144107616411299&w=2]: >> >> > I made a very deliberate decision In the very first implementation of >> PHP to avoid scope side-effects like this. Inside a function everything is >> local unless explicitly declared not to be. This has carried through for the >> past 20+ years in slightly different ways, but the basic rule has stayed >> consistent even for closures. > > > Ok, it proves that it's not evolutionary that scopes aren't chained. Taking > my words back. > > >> It is a tool for making them shorter, yes, but it is not the only way, and >> it comes with a cost of changing established behaviour. Again, look at C++'s >> lambda syntax - it is much shorter than PHP's, but requires a list of all >> variables from the outer scope being captured. > > > C++11 doesn't *require* the list of all variables, but it does require > explicit "wildcard" ([=] for copy semantics, [&] for capturing by > reference). > But C++ is not the best place for picking up syntax choices, quite frankly > it's one of the least readable languages in a way that it allows you to > write very cryptic code easily (but still allows to write perfectly readable > code as well). > I'm not aware of reasons why ISOCPP decided that automatic capture should be > disabled by default, maybe it was because it was hard to decide whether it > should default to by-value or to by-reference semantics, or maybe [] tokens > were needed because of parsing limitations. > > >> You've picked on one syntax I explicitly labelled as "a straw man", and >> one idea which was proposed by somebody else a few hours ago, and use those >> to somehow dismiss the whole idea of a short syntax which lists captured >> variables. I have come up with about a dozen different ideas in various >> parts of this discussion, and could list dozens more. They would all have >> their pros and cons, but I don't see how you can dismiss the whole concept, >> UNLESS you consider the auto-capture to be an end in its own right, rather >> than "just a way of making it shorter". > > > I don't think there was a dozen of different ideas, I could only find those > about lambda(arg-list; use-list; expression) and variations of > it with > different keywords and different return-type syntax. > I do understand that this is quite subjective, but neither this syntax nor > fn(arg-list; use-list) expression look obvious and easily > readable to me. The problem is that semicolons are non-obvious, especially in a context where commas are used (and traditionally used). Example, tell the difference quickly between fn($a, $b; $c) => $a + $b + $c; and fn($a; $b, $c) => $a + $b + $c. At a glance, they are identical. You have to actually look at each item to realize that there's a difference. At least with use() there's a syntactical separator there to draw your eye to the contextually relevant information.