assert with format considered harmful

[Nick Sabalausky (Abscissa) via Digitalmars-d]

On 02/26/2017 02:17 AM, Seb wrote:
> On Sunday, 26 February 2017 at 06:34:07 UTC, Ali Çehreli wrote:
>> So, obviously, assert message generation is not lazy. This is a WAT!
>> for me but perhaps there is a good reason for it.
>
> FWIW imho we shouldn't need to write such messages at all.
> It shouldn't be to difficult to lower `assert (a BINOP b)` into sth. like:
>
> (auto ref a, auto ref b) {
>      if (a BINOP b) return;
>      onAssertFailed!"BINOP"(a, b, __FILE__, __LINE__, __FUNCTION__,
> __MODULE__);
> } (e1, e2);
>
> with onAssertFailed being a nice pretty-printer in the direction of:
>
> assert([1,2,3] == [1,2,4]); // ERROR: ([1,2,3][2] is 3) != ([1,2,4][2]
> is 4)
> struct A { int x, y; }
> auto a = A(1,2);
> auto b = A(1,3);
> assert(a == b);  // ERROR: (a.y is 2) != (b.y is 3)
>
> This idea is formally known as DIP83:
>
> https://wiki.dlang.org/DIP83

Yea. Six years ago, assertPred was written for Phobos and rejected 
because it was decided it was better for assert to just gain that 
functionality built-in...which a full six years later, never happened. 
Letting perfect be the enemy of the good, at its golden finest.