Re: is this a betterC bug ?
On Wednesday, 15 August 2018 at 08:14:53 UTC, Petar Kirov
[ZombineDev] wrote:
It's not a bug, it's all about how the type system is set up.
The type of an array literal expression like `[1, 2, 3]` is
`int[]` (a slice of an array of ints), so no matter if you do:
auto readonly(T)(const(T)[] x) { return x; }
auto arr1 = [1, 2, 3];
auto arr2 = [1, 2, 3].readonly;
constarr3 = [1, 2, 3];
enum arr4 = [1, 2, 3];
static immutable arr5 = [1, 2, 3];
scopearr6 = [1, 2, 3];
In all instances the type will be `int[]` modulo type
qualifiers.
Static arrays are completely different types, that just happen
to accept
assignments from slices. Their two defining properties are:
1. Their length is fixed at compile-time, meaning that you can
do:
import std.array, std.meta;
auto x = [1, 2, 3, 4, 5].staticArray;
enum length = x.length;
pragma (msg, length);
alias seq = AliasSeq!(0, 42, length);
static foreach (i; 0 .. length) { }
static foreach (i; seq) { }
2. Where slices are reference types, static arrays are value
types which means that each assignment will copy an entire
array.
Basically they behave like a `struct { int _arr_0 = 0, _arr_1 =
1, _arr_2 = 2; }`.
https://run.dlang.io/is/iD9ydu
Thanks for the detailed explanation; it make sense now.
Mike
Re: is this a betterC bug ?
On Wednesday, 15 August 2018 at 08:14:53 UTC, Petar Kirov [ZombineDev] wrote: https://run.dlang.io/is/iD9ydu I made a typo in one of the comments. Here's the fixed version: https://run.dlang.io/is/HRqYcZ
Re: is this a betterC bug ?
On Tuesday, 14 August 2018 at 17:49:32 UTC, Mike Franklin wrote:
On Tuesday, 14 August 2018 at 17:22:42 UTC, Seb wrote:
FYI: staticArray will be part of 2.082, it already works with
dmd-nightly:
That just seems wrong. Isn't the fact that `staticArray` is
needed a bug in the compiler? I think the compiler could have
lowered to something like that automatically to avoid the
library workaround.
Mike
It's not a bug, it's all about how the type system is set up. The
type of an array literal expression like `[1, 2, 3]` is `int[]`
(a slice of an array of ints), so no matter if you do:
auto readonly(T)(const(T)[] x) { return x; }
auto arr1 = [1, 2, 3];
auto arr2 = [1, 2, 3].readonly;
constarr3 = [1, 2, 3];
enum arr4 = [1, 2, 3];
static immutable arr5 = [1, 2, 3];
scopearr6 = [1, 2, 3];
In all instances the type will be `int[]` modulo type qualifiers.
Static arrays are completely different types, that just happen to
accept
assignments from slices. Their two defining properties are:
1. Their length is fixed at compile-time, meaning that you can do:
import std.array, std.meta;
auto x = [1, 2, 3, 4, 5].staticArray;
enum length = x.length;
pragma (msg, length);
alias seq = AliasSeq!(0, 42, length);
static foreach (i; 0 .. length) { }
static foreach (i; seq) { }
2. Where slices are reference types, static arrays are value
types which means that each assignment will copy an entire array.
Basically they behave like a `struct { int _arr_0 = 0, _arr_1 =
1, _arr_2 = 2; }`.
https://run.dlang.io/is/iD9ydu
Re: is this a betterC bug ?
On Tuesday, 14 August 2018 at 17:22:42 UTC, Seb wrote: FYI: staticArray will be part of 2.082, it already works with dmd-nightly: That just seems wrong. Isn't the fact that `staticArray` is needed a bug in the compiler? I think the compiler could have lowered to something like that automatically to avoid the library workaround. Mike
Re: is this a betterC bug ?
On Tuesday, 14 August 2018 at 16:31:38 UTC, Paul Backus wrote:
On Tuesday, 14 August 2018 at 13:01:57 UTC, learnfirst1 wrote:
enum string[] a = ["a"];
extern(C) void main() {
int i = 0;
auto s = a[i];
}
---
Error: TypeInfo cannot be used with -betterC
Workaround: https://run.dlang.io/is/NZykl0
Source: https://p0nce.github.io/d-idioms/
FYI: staticArray will be part of 2.082, it already works with
dmd-nightly:
https://run.dlang.io/is/tC7tix
Re: is this a betterC bug ?
On Tuesday, 14 August 2018 at 13:01:57 UTC, learnfirst1 wrote:
enum string[] a = ["a"];
extern(C) void main() {
int i = 0;
auto s = a[i];
}
---
Error: TypeInfo cannot be used with -betterC
Workaround: https://run.dlang.io/is/NZykl0
Source: https://p0nce.github.io/d-idioms/
Re: is this a betterC bug ?
On Tuesday, 14 August 2018 at 13:01:57 UTC, learnfirst1 wrote:
enum string[] a = ["a"];
extern(C) void main() {
int i = 0;
auto s = a[i];
}
---
Error: TypeInfo cannot be used with -betterC
You can use `static immutable` as a workaround for now:
https://run.dlang.io/is/7HEPst
Re: is this a betterC bug ?
On Tuesday, 14 August 2018 at 13:16:50 UTC, Nicholas Wilson wrote:
On Tuesday, 14 August 2018 at 13:01:57 UTC, learnfirst1 wrote:
enum string[] a = ["a"];
extern(C) void main() {
int i = 0;
auto s = a[i];
}
---
Error: TypeInfo cannot be used with -betterC
Yes. https://issues.dlang.org/show_bug.cgi?id=19169
This seems to be because dynamic array literals are allocated by
default. So that is possibly not a bug, per se but the error
message is definitely not helpful.
Re: is this a betterC bug ?
On Tuesday, 14 August 2018 at 13:01:57 UTC, learnfirst1 wrote:
enum string[] a = ["a"];
extern(C) void main() {
int i = 0;
auto s = a[i];
}
---
Error: TypeInfo cannot be used with -betterC
Yes. https://issues.dlang.org/show_bug.cgi?id=19169
