On 6/5/22 04:43, kdevel wrote:
> On Sunday, 5 June 2022 at 00:40:26 UTC, Ali Çehreli wrote:
> [...]
>> Errors are thrown when the program is discovered to be in an invalid
>> state.
>
> The following program throws an `Error` in popFront:
>
> import std.range;
>
> void main ()
> {
> int [1] a;
> auto q = a[1..$]; // line 6
> q.popFront; // line 7, throws core.exception.AssertError
> }
>
> When the program counter (PC) is at line 6 the program is in a valid
state.
>
> At no time the program is in an invalid state and it would not pass into
> an invalid state if popFront threw an `Exception` instead of an `Error`.
That looks like an argument for changing the behavior of D runtime when
an out-of-bounds access occurs. Of course, it is too late to change that
at this time but perhaps there can be a compiler switch like
-boundstype=[error|exception].
The programmer has many options to prove that nothing crazy is
happening. A common example suitable for many cases:
enforce(!q.empty); // (Throws Exception)
q.popFront;
Ali
