Re: null coalesce addition assignment operator ??+=

Some background / personal experience (cross-posting with Stanislav, but I am sending it anyway) I regularly see code with arrays in loops, where the ??+= or ??++ would be nice to have. I do not remember seeing use cases for *=. In all the cases I remember, the left side was an array offset, not a plain variable. I think the spec has to be for plain variables first, even if the main use case is arrays. I only added the ??*=, ??-=, ??++, ??-- for completeness, but I can live without. On 18 January 2018 at 23:58, Stanislav Malyshev <smalyshev@gmail.com> wrote: > I think this is taking it too far. If you want language like that, you > always have APL :) It looks a bit cluttery (one character too many for an operator?), but I think it is useful and intuitive. If you understand ??, ??= and +=, you also understand ??+=. But let's see what others say. On 18 January 2018 at 23:52, Andreas Hennings <andreas@dqxtech.net> wrote: > The "Null Coalescing Assignment Operator" (or null coalesce assignment > operator) was proposed and accepted in > https://wiki.php.net/rfc/null_coalesce_equal_operator > > I propose even more such operators: > null coalesce addition assignment ??+= (for strings and numbers) > null coalesce subtraction assignment ??-= > null coalesce increment ??++ > null coalesce decrement ??-- > null coalesce multiplication assingment ??*= > > > ## Details > > Each block contains 3 equivalent statements. > > $x ??+= 5; // proposed new syntax > ($x ??= 0) += 5; // syntax with null coalesce assignment operator > $x = ($x ?? 0) + 5; // syntax with simple null coalesce operator > > $x ??+= 'suffix'; // proposed new syntax > ($x ??= '') += 'suffix'; // syntax with null coalesce assignment operator > $x = ($x ?? '') + 'suffix'; // syntax with simple null coalesce operator > > $x ??++; // proposed new syntax > ($x ??= 0)++; > $x = ($x ?? 0) + 1; > > $x ??*= 2; // proposed new syntax > ($x ??= 1) *= 2; > $x = ($x ?? 1) * 2; > > Note that in each case PHP needs to determine the "neutral element" of > the operation. > For string concat this is the empty string. For number addition this > is 0. For number multiplication it is 1. > > > ## Example: > > For me, the most common use case would be something like this: > > $fruitpacks = [ > ['apples', 3], > ['pears', 1], > ['apples', 6], > ['grapes', 22], > ]; > > $totals_by_name = []; > foreach ($fruitpacks as [$name, $amount]) { > $totals_by_name[$name] ??+= $amount; // proposed new syntax > } > > $totals_by_name_expected = [ > 'apples' => 9, > 'pears' => 1, > 'grapes' => 22, > ]; > > assert($totals_by_name === $totals_by_name_expected); > > > ## Notes > > In PHP, the "+=" operator already behaves almost like "??+=", but adds > a "Notice: Undefined offset" or "Notice: Undefined variable", if the > left side is not defined yet. > hhvm apparently does not produce this notice. > https://3v4l.org/l0l0K