DIP 1003 Formal Review

[Jonathan M Davis via Digitalmars-d]

On Tuesday, May 16, 2017 17:22:12 Timon Gehr via Digitalmars-d wrote:
> On 15.05.2017 03:18, Jonathan M Davis via Digitalmars-d wrote:
> > So, while I do like the idea of getting the word body back as an
> > identifier, what really appeals to me here is getting rid of the need
> > for it with contracts.
>
> auto foo()in{
>      assert(true);
> }out{
>      assert(true);
> }{
>      return 3;
> }
>
> Are you really arguing for this?
> I don't want to write code like this.

Well, I can't say that I like the formatting, but most definietly I am
arguing for that. Right now, just because you add contracts, you suddenly
have to add an extra keyword that is unnecessary when there are no contracts
and which is redundant. You go from having something like

auto foo(T param)
{
    ...
}

to something like

auto foo(T param)
in
{
    assert(...);
}
out(result)
{
    assert(...);
}
body
{
    ...
}

or

auto foo(T param)
in { assert(...); }
out(result) { assert(...); }
body
{
    ...
}

or however you want to format it. But the last set of braces is always the
function body just like it is when there are no contracts. And having to
have body (or function whatever other keyword we might put there) just makes
contracts that much more verbose - as well as being inconsistent with how
functions bodies are declared when there are no contracts.

Honestly, as nice as it would be to get the body keyword back as an
identifier, I care _way_ more about not having a redundant keyword for the
function body. I'd be all for removing it from contracts even if we never
got it back as an identifier. I've always found needing to add body to be
very annoying, and I frequently forget it, because it's not there normally.
It's just making contracts longer without adding extra information, and
contracts are _way_ too verbose even without the extra keyword there, let
alone with it.

IMHO, if we remove body as a keyword but replace it with something else in
contracts, we've lost out on a big opportunity for some language cleanup.

- Jonathan M Davis