[dmd-internals] AssociativeArray in druntime should go before the next release

[Steve Schveighoffer]

I'd much rather fix implicit storage of literals than incur both template bloat and have to deal with type deduction.  Besides the heap allocation issue, the rewrite that Don put forth already uses the compiler to type deduce the array types (and therefore the key and value types) without any excessive template bloat.  I'm assuming you meant something like:

SomeRecursiveTemplateToDeduceKeyAndValue!(T) AALiteral(T...)(T vals) if (vals.length % 2 == 0 && SomeRecursiveTemplateToEnsureKeyAndValueExist!(T))

What I was thinking is making something like:

void foo(scope int[]) {}
not allocate the argument to foo on the heap if it's a literal.


-Steve



----- Original Message -----
> From: Andrei Alexandrescu <andrei at erdani.com>
> To: Steve Schveighoffer <schveiguy at yahoo.com>; Discuss the internals of DMD <dmd-internals at puremagic.com>
> Cc: 
> Sent: Friday, February 3, 2012 6:25 PM
> Subject: Re: [dmd-internals] AssociativeArray in druntime should go before the next release
> 
> On 2/3/12 2:28 PM, Steve Schveighoffer wrote:
>>  What I am saying is, if we go with the lowering of:
>> 
>>  [a:b, c:d] =>  AALiteral([a,c], [b,d]);
>> 
>>  I would like to have this not needlessly allocate the arrays [a, c] and [b, 
> d] on the heap, since those arrays will be unused after that call.  To use the 
> heap would be a step backwards, since the current AA literal code does not use 
> it.
>> 
>>  -Steve
> 
> I think the language is powerful enough to afford us the rewrite:
> 
> [a:b, c:d] => aaLiteral(a, b, c, d)
> 
> 
> Andrei
>