On 9/3/20 10:43 AM, Jesse Phillips wrote:
On Tuesday, 1 September 2020 at 18:55:20 UTC, Steven Schveighoffer wrote:
On 9/1/20 2:20 PM, Jesse Phillips wrote:
Using RangeError is nice as it allows code to use array index inside
`nothrow.`
This is the big sticking point -- code that is nothrow would no longer
be able to use AAs. It makes the idea, unfortunately, a non-starter.
What is wrong with using `in`? I use this mostly:
if(auto v = key in aa) { /* use v */ }
I think that actually might be my point. If you need nothrow then this
is what you need to do.
For breaking nothrow code using the [] syntax, I'd say it is already
broken because the behavior is to throw and the above is how you would
check that it won't.
int[int] aa;
aa[4] = 5;
auto b = aa[4];
How is this code broken? It's valid, will never throw, and there's no
reason that we should break it by adding an exception into the mix.
The issue is, associative arrays throw an "uncatchable" error. Meaning
code is written to catch the error (because it works). And correctly
written `nothrow` code needs to use `in` to be properly nothrow.
The big issue is -- is accessing an invalid index a programming error or
an environmental error? The answer is -- it depends. D has declared, if
you use the indexing syntax, then it's a programming error. If you want
it not to be a programming error, you use the key in aa syntax, and
handle it.
The other thing you can do is use a different type, if you don't want to
deal with the verbose syntax, but still want to catch environmental
errors. A wrapper type is possible.
-Steve
