Template instantiation syntax

[Bill Baxter]

On Sun, Oct 12, 2008 at 11:07 AM, Andrei Alexandrescu
<SeeWebsiteForEmail at erdani.org> wrote:
> Bill Baxter wrote:
>>
>> On Sun, Oct 12, 2008 at 10:46 AM, bearophile <bearophileHUGS at lycos.com>
>> wrote:
>>>
>>> Jarrett Billingsley:
>>>>
>>>> It's not "error-prone", it's "you're not used to it."  You very
>>>> commonly fall into the fallacy that if you think something's
>>>> bad/confusing/not what you're used to, then _everyone_ must think that
>>>> way and therefore it _must_ change.  Sorry, that's not the way it
>>>> works.  I haven't mistyped a foreach loop, ever.  Deal with it.
>>>
>>> I remember that when I have discussed about this topic the first time
>>> another person has said of sharing this problem of mine with this syntax.
>>>
>>> C# foreach syntax uses the "in", and Python too uses it. Both languages
>>> are quite more used than D, are modern, and they care about their usability
>>> and readability.
>>>
>>> If I don't talk about this topic I can't know if it's a common problem,
>>> or a personal one.
>>>
>>> So even if I am wrong (and I am wrong all the time), and the current
>>> foreach syntax of D isn't bug-prone, I think the topic deserves a little
>>> discussion, so people can show who's right.
>>
>> I agree with you, Bearophile.  And I may be the person you remember
>> agreeing with you before.  So we may be the only two.  :-)   Although
>> clearly designers of C# and Python thought it looked nicer than other
>> possibilities, so apparently they agree too.
>>
>> But anyway it seems not to be an easy change to make it work in D
>> without ruining the easy syntax parsing.  So another idea for
>> unambiguous syntax is needed.   An 'of' keyword or make an
>> in-expression or something.
>>      foreach(x of thinglist) { ... }
>>      foreach(x in(thinglist)) { ... }
>>      foreach(x (in) thinglist) { ... }
>>
>> But even then, the result has to be so much better than ";" that it's
>> worth breaking backwards compatibility.  I think that's a hard sell.
>> ";" works and its not totally terrible, and it does have precedent
>> with the semicolons in regular for loops.
>
> I don't see any technical difficulty with allowing foreach (x in y).

Walter seems to think there is for some reason.  Maybe because of
foreach(x in y in z) ?

--bb