I know that according to language spec (https://dlang.org/spec/arrays.html#static-init-static) you can skip declaring all your elements in a fixed size array.

I'm just recovering from a bug which took me one day to discover because of this.

I have a large static initialized array, let's say int[155], and I forgot to declare the last element:

int[155] myarray = [
  a,
  b,
  c,
  ...
  //forgot to declare the 155th element
];

I took for granted that the compiler will warn me about the fact that my number of elements doesn't match the array declaration but I was wrong.

Does it worth to fill an enhancement on this, or this is intended behavior?

On Saturday, 10 February 2018 at 10:55:30 UTC, rumbu wrote:
> I know that according to language spec (https://dlang.org/spec/arrays.html#static-init-static) you can skip declaring all your elements in a fixed size array.
>
> I'm just recovering from a bug which took me one day to discover because of this.
>
> I have a large static initialized array, let's say int[155], and I forgot to declare the last element:
>
> int[155] myarray = [
>   a,
>   b,
>   c,
>   ...
>   //forgot to declare the 155th element
> ];
>
> I took for granted that the compiler will warn me about the fact that my number of elements doesn't match the array declaration but I was wrong.
>
> Does it worth to fill an enhancement on this, or this is intended behavior?

I used to agree (https://issues.dlang.org/show_bug.cgi?id=17341) and even patched the compiler to emit a deprecation in this case. Then i discovered that druntime for example relies on this.

The classic use case is to init a LUT where only a few elements need a non-default value, for example:

```
bool[char.max] lut = [10:true, 13:true, 9: true];
assert(!lut[46]);
assert(lut[9]);
```

which can be useful.

https://issues.dlang.org/show_bug.cgi?id=481#c40

On Saturday, 10 February 2018 at 12:28:16 UTC, b2.temp wrote:
> On Saturday, 10 February 2018 at 10:55:30 UTC, rumbu wrote:
>> I know that according to language spec (https://dlang.org/spec/arrays.html#static-init-static) you can skip declaring all your elements in a fixed size array.
>>
>> I'm just recovering from a bug which took me one day to discover because of this.
>>
>> I have a large static initialized array, let's say int[155], and I forgot to declare the last element:
>>
>> int[155] myarray = [
>>   a,
>>   b,
>>   c,
>>   ...
>>   //forgot to declare the 155th element
>> ];
>>
>> I took for granted that the compiler will warn me about the fact that my number of elements doesn't match the array declaration but I was wrong.
>>
>> Does it worth to fill an enhancement on this, or this is intended behavior?
>
> I used to agree (https://issues.dlang.org/show_bug.cgi?id=17341) and even patched the compiler to emit a deprecation in this case. Then i discovered that druntime for example relies on this.
>
> The classic use case is to init a LUT where only a few elements need a non-default value, for example:
>
> ```
> bool[char.max] lut = [10:true, 13:true, 9: true];
> assert(!lut[46]);
> assert(lut[9]);
> ```
>
> which can be useful.

In this case, it there any way to be sure that I declared all the elements I intended? Obviously, without counting them by hand.

On Saturday, 10 February 2018 at 14:35:52 UTC, rumbu wrote:
> On Saturday, 10 February 2018 at 12:28:16 UTC, b2.temp wrote:
>> On Saturday, 10 February 2018 at 10:55:30 UTC, rumbu wrote:
>>> I know that according to language spec (https://dlang.org/spec/arrays.html#static-init-static) you can skip declaring all your elements in a fixed size array.
>>>
>>> I'm just recovering from a bug which took me one day to discover because of this.
>>>
>>> I have a large static initialized array, let's say int[155], and I forgot to declare the last element:
>>>
>>> int[155] myarray = [
>>>   a,
>>>   b,
>>>   c,
>>>   ...
>>>   //forgot to declare the 155th element
>>> ];
>>>
>>> I took for granted that the compiler will warn me about the fact that my number of elements doesn't match the array declaration but I was wrong.
>>>
>>> Does it worth to fill an enhancement on this, or this is intended behavior?
>>
>> I used to agree (https://issues.dlang.org/show_bug.cgi?id=17341) and even patched the compiler
>>to emit a deprecation in this case. Then
>> i discovered that druntime for example relies on this.
>>
>> The classic use case is to init a LUT where only a few elements need a non-default value, for example:
>>
>> ```
>> bool[char.max] lut = [10:true, 13:true, 9: true];
>> assert(!lut[46]);
>> assert(lut[9]);
>> ```
>>
>> which can be useful.
>
> In this case, it there any way to be sure that I declared all the elements I intended? Obviously, without counting them by hand.

At the level of the library use a template.

At the level of the compiler: no. Not only not all elements are required but they also don't need to be declared in order (static array initialization, like in the example beyond).

It would be possible to put a compiler warning but warnings are not in the D philosophy (one consequence is that many people, like me use -de all the time, making a possible warning not compatible with the legit uses of the "partial array initialization").

By the way i said i did change the compiler. Actually i even captured the session to promote my IDE: http://sendvid.com/c00x7nps.

On Saturday, 10 February 2018 at 14:55:49 UTC, b2.temp wrote:
> On Saturday, 10 February 2018 at 14:35:52 UTC, rumbu wrote:
>>
>> In this case, it there any way to be sure that I declared all the elements I intended? Obviously, without counting them by hand.
>
> At the level of the library use a template.

Sorry, but I don't get it. Can you elaborate, please?

This is the array in question: https://github.com/rumbu13/decimal/blob/master/src/decimal/integrals.d#L2072

First time, I tried to use mixins to generate the array, in order to avoid writing the same thing again and again. The mixin solution was nice until the compiler served me a nice Out of Memory error, that's why I finally used a hand-written array.

>
> At the level of the compiler: no. Not only not all elements are required but they also don't need to be declared in order (static array initialization, like in the example beyond).
>
> It would be possible to put a compiler warning but warnings are not in the D philosophy (one consequence is that many people, like me use -de all the time, making a possible warning not compatible with the legit uses of the "partial array initialization").
>
> By the way i said i did change the compiler. Actually i even captured the session to promote my IDE: http://sendvid.com/c00x7nps.

On Saturday, 10 February 2018 at 15:54:03 UTC, rumbu wrote:
> On Saturday, 10 February 2018 at 14:55:49 UTC, b2.temp wrote:
>> On Saturday, 10 February 2018 at 14:35:52 UTC, rumbu wrote:
>>>
>>> In this case, it there any way to be sure that I declared all the elements I intended? Obviously, without counting them by hand.
>>
>> At the level of the library use a template.
>
> Sorry, but I don't get it. Can you elaborate, please?

https://github.com/dlang/phobos/pull/4936

On Saturday, 10 February 2018 at 10:55:30 UTC, rumbu wrote:
>
> I have a large static initialized array, let's say int[155], and I forgot to declare the last element:
>
> int[155] myarray = [
>   a,
>   b,
>   c,
>   ...
>   //forgot to declare the 155th element
> ];


Well, in C.. I can do:

int arr[2] = { [0]=10, [1]=20 };

I cannot work out how to do that in D yet (anyone know??)

In the meantime, I'd suggest doing it this way, as you're more likely to see that whether you forgot an element:

int[2] arr;
    {
        arr[0] = 10;
        arr[1] = 20;
    }

On Sunday, 11 February 2018 at 01:13:00 UTC, psychoticRabbit wrote:
>
> Well, in C.. I can do:
>
> int arr[2] = { [0]=10, [1]=20 };
>
> I cannot work out how to do that in D yet (anyone know??)
>

Oh. just worked it out after reading this thread ;-)

int[2] arr = [ 0:10, 1:20 ];

On Sunday, 11 February 2018 at 01:26:59 UTC, psychoticRabbit wrote:
> On Sunday, 11 February 2018 at 01:13:00 UTC, psychoticRabbit wrote:
>>
>> Well, in C.. I can do:
>>
>> int arr[2] = { [0]=10, [1]=20 };
>>
>> I cannot work out how to do that in D yet (anyone know??)
>>
>
> Oh. just worked it out after reading this thread ;-)
>
> int[2] arr = [ 0:10, 1:20 ];

This is indeed the most simple and elegant solution. Thanks.