http://minas-mina.com/2016/01/01/associative-arrays/

https://www.reddit.com/r/programming/comments/3z03ji/hash_tables_in_the_d_programming_language/

On Friday, 1 January 2016 at 13:59:35 UTC, Walter Bright wrote:
> http://minas-mina.com/2016/01/01/associative-arrays/
>
> https://www.reddit.com/r/programming/comments/3z03ji/hash_tables_in_the_d_programming_language/

Thanks for sharing this. I am the author. :)

On 1/1/2016 7:27 AM, Minas Mina wrote:
> On Friday, 1 January 2016 at 13:59:35 UTC, Walter Bright wrote:
>> http://minas-mina.com/2016/01/01/associative-arrays/
>>
>> https://www.reddit.com/r/programming/comments/3z03ji/hash_tables_in_the_d_programming_language/
>>
>
> Thanks for sharing this. I am the author. :)

You're welcome, and thanks for writing the nice article.

On 01/01/2016 04:27 PM, Minas Mina wrote:
> On Friday, 1 January 2016 at 13:59:35 UTC, Walter Bright wrote:
>> http://minas-mina.com/2016/01/01/associative-arrays/
>>
>> https://www.reddit.com/r/programming/comments/3z03ji/hash_tables_in_the_d_programming_language/
>>
> 
> Thanks for sharing this. I am the author. :)

There is a bug.

You should never do this b/c of iterator/range invalidation.

foreach (key; aa.keys)
    aa.remove(key);

On Sunday, 3 January 2016 at 19:29:05 UTC, Martin Nowak wrote:
> On 01/01/2016 04:27 PM, Minas Mina wrote:
>> On Friday, 1 January 2016 at 13:59:35 UTC, Walter Bright wrote:
>>> http://minas-mina.com/2016/01/01/associative-arrays/
>>>
>>> https://www.reddit.com/r/programming/comments/3z03ji/hash_tables_in_the_d_programming_language/
>>>
>> 
>> Thanks for sharing this. I am the author. :)
>
> There is a bug.
>
> You should never do this b/c of iterator/range invalidation.
>
> foreach (key; aa.keys)
>     aa.remove(key);

The reference states that keys: "Returns dynamic array, the elements of which are the keys in the associative array".

Isn't the array newly allocated?

On Monday, 4 January 2016 at 07:09:30 UTC, Minas Mina wrote:
> On Sunday, 3 January 2016 at 19:29:05 UTC, Martin Nowak wrote:
>>
>> There is a bug.
>>
>> You should never do this b/c of iterator/range invalidation.
>>
>> foreach (key; aa.keys)
>>     aa.remove(key);
>
> The reference states that keys: "Returns dynamic array, the elements of which are the keys in the associative array".
>
> Isn't the array newly allocated?


Hi,

You are right:

> void main()
> {
> 	import std.stdio;
> 	int[int] aa;
> 	foreach (i; 0..9)
> 		aa[i] = i * 10;
> 	writeln(aa); // [0:0, 6:60, 7:70, 2:20, 3:30, 1:10, 8:80, 5:50, 4:40]
> 
> 	foreach (key; aa.keys)
> 		aa.remove(key);
> 	writeln(aa); // []
> }

This would be a bug (segfault on my machine):

> 	foreach (key; aa.byKey)
> 		aa.remove(key);

Note that, in this example, there is no need to remove every element separately, you can also just do

> void main()
> {
> 	import std.stdio;
> 	int[int] aa;
> 	foreach (i; 0..9)
> 		aa[i] = i * 10;
> 	writeln(aa); // [0:0, 6:60, 7:70, 2:20, 3:30, 1:10, 8:80, 5:50, 4:40]
> 
> 	aa = null;
> 	writeln(aa); // []
> }

Bastiaan.

On 01/04/2016 09:06 AM, Bastiaan Veelo wrote:
> 
> This would be a bug (segfault on my machine):
> 
>>     foreach (key; aa.byKey)
>>         aa.remove(key);
> 
> Note that, in this example, there is no need to remove every element separately, you can also just do

Sorry my mistake, I never use aa.keys (instead of aa.byKey) b/c it
allocates.
So it's still sort of a bug to recommend people allocating an array ;).

On Monday, 4 January 2016 at 19:58:03 UTC, Martin Nowak wrote:
> On 01/04/2016 09:06 AM, Bastiaan Veelo wrote:
>> 
>> This would be a bug (segfault on my machine):
>> 
>>>     foreach (key; aa.byKey)
>>>         aa.remove(key);
>> 
>> Note that, in this example, there is no need to remove every element separately, you can also just do
>
> Sorry my mistake, I never use aa.keys (instead of aa.byKey) b/c it
> allocates.
> So it's still sort of a bug to recommend people allocating an array ;).


I haven't found a way to clear an AA without allocating though.
(Creating a new one doesn't count).

On 2016-01-05 11:19, Minas Mina wrote:

> I haven't found a way to clear an AA without allocating though.
> (Creating a new one doesn't count).

Set it to "null", or will that allocate a new one?

-- 
/Jacob Carlborg

On Tuesday, 5 January 2016 at 13:36:48 UTC, Jacob Carlborg wrote:
> On 2016-01-05 11:19, Minas Mina wrote:
>
>> I haven't found a way to clear an AA without allocating though.
>> (Creating a new one doesn't count).
>
> Set it to "null", or will that allocate a new one?

It won't, but to use it again you need to allocate a new one (If I'm not mistaken).