Re: More useful fixed-size array literals

[Benjamin Thaut via Digitalmars-d]

Am 31.05.2014 00:19, schrieb bearophile:
Code similar to this is not uncommon. Currently it's refused:

immutable data = [1, 5, 3, 1, 5, 1, 5];
void main() @nogc {
     import std.algorithm: count;
     assert(data.count([1, 5]) == 3);
}


test.d(4,23): Error: array literal in @nogc function main may cause GC
allocation


The current workaround is not handy when you have conditionals, etc:

immutable data = [1, 5, 3, 1, 5, 1, 5];
void main() @nogc {
     import std.algorithm: count;
     immutable static part = [1, 5];
     assert(data.count(part) == 3);
}


A language solution is a literal syntax for fixed-sized arrays (here I
slice it again because unfortunately count doesn't accept fixed-sized
arrays):


immutable data = [1, 5, 3, 1, 5, 1, 5];
void main() @nogc {
     import std.algorithm: count;
     assert(data.count([1, 5]s[]) == 3);
}


I remember Kenji is not fond of this []s syntax, for reasons I don't
remember. Do you think there are other better/different solutions?

Bye,
bearophile


give "scope" a meaning for function arguments other then lambdas E.g:

size_t count(scope int[] heystack, scope int[] needle);

Now the compiler can allocate the literal [1, 5] on the stack without 
any special syntax because it knows that the array literal will not be 
escaped.

Kind Regards
Benjamin Thaut