Associative arrays give compile error

[Denis Koroskin]

On Tue, 05 Oct 2010 15:53:55 +0400, Denis Koroskin <2korden at gmail.com>  
wrote:

> On Tue, 05 Oct 2010 15:40:39 +0400, Bob Cowdery  
> <bob at bobcowdery.plus.com> wrote:
>
>>  On 05/10/2010 12:13, Denis Koroskin wrote:
>>> On Tue, 05 Oct 2010 15:08:39 +0400, Bob Cowdery
>>> <bob at bobcowdery.plus.com> wrote:
>>>
>>>>  On 05/10/2010 12:04, Denis Koroskin wrote:
>>>>> On Tue, 05 Oct 2010 14:57:22 +0400, Bob Cowdery
>>>>> <bob at bobcowdery.plus.com> wrote:
>>>>>
>>>>>>  On 05/10/2010 11:45, Denis Koroskin wrote:
>>>>>>> On Tue, 05 Oct 2010 14:23:47 +0400, Bob Cowdery
>>>>>>> <bob at bobcowdery.plus.com> wrote:
>>>>>>>
>>>>>>>>  I can't seem to get any sense out of associative arrays. Even the
>>>>>>>> simplest definition won't compile so I must be doing something  
>>>>>>>> daft.
>>>>>>>>
>>>>>>>> int[string] aa = ["hello":42];
>>>>>>>>
>>>>>>>> Error: non-constant expression ["hello":42]
>>>>>>>>
>>>>>>>> What exactly is not constant about this. The example is straight
>>>>>>>> out the
>>>>>>>> book. Using D 2.0.
>>>>>>>>
>>>>>>>> bob
>>>>>>>
>>>>>>> What exactly compiler version are you using (run dmd with no args)?
>>>>>>> Works perfectly fine here (dmd2.049).
>>>>>>
>>>>>> It says 2.049. How odd. I've got a fair amount of code and  
>>>>>> everything
>>>>>> else compiles fine.
>>>>>
>>>>> Can you please post complete code snippet that fails to compile?
>>>>>
>>>>> Here is the code I used to test:
>>>>>
>>>>> module aa;
>>>>>
>>>>> import std.stdio;
>>>>>
>>>>> void main()
>>>>> {
>>>>>     int[string] aa = ["hello":42];
>>>>>     writeln(aa["hello"]);
>>>>> }
>>>>>
>>>>> # dmd -run aa.d
>>>>
>>>> Ah! It's some other code below it that is not giving an error but
>>>> causing the error above. So the compiler is getting confused. What I  
>>>> was
>>>> actually trying to do was create an associative array with a string  
>>>> as a
>>>> key and a Tuple as the value. Now
>>>>
>>>> auto aa = [
>>>>     "some string": (100.0, 6100.0)
>>>> ]
>>>>
>>>> compiles but is clearly wrong and gives rise to other errors.  Does
>>>> anyone know the correct way to define this and then access the tuple.
>>>
>>> import std.stdio;
>>> import std.typecons;
>>>
>>> void main()
>>> {
>>>     auto aa = ["hello": tuple(100.0, 6100.0)];
>>>     auto result = aa["hello"];
>>>
>>>     writeln(result.field[0], " ", result._1); // primary and
>>> alternative way
>>> }
>>
>> Thanks. I've established that works for me and also that the actual
>> array I'm using also works in the test program but it won't compile in
>> the real program. I've commented everything else out of the file and
>> just left...
>>
>> import std.typecons;
>>
>> auto A_RX_FILT = [
>>     "6K0": tuple(100.0, 6100.0),
>>     "2K4": tuple(300.0, 2700.0),
>>     "2K1": tuple(300.0, 2400.0),
>>     "1K0": tuple(300.0, 1300.0),
>>     "500": tuple(500.0, 1000.0),
>>     "250": tuple(600.0, 850.0),
>>     "100": tuple(700.0, 800.0)
>> ];
>>
>
> You are trying to declare global variable and initialize at in compile  
> time. As far as I know, you can't initialize AA at compile time atm  
> (this might be implemented in future though).
>
> As such, I'd recommend against using global variables (try moving it to  
> some class or something). Anyway, you need to initialize it at some  
> point, either manually:
>
> Tuple!(double,double)[string] A_RX_FILT;
>
> void init()
> {
>      A_RX_FILT = [
> 	"6K0": tuple(100.0, 6100.0),
> 	"2K4": tuple(300.0, 2700.0),
> 	"2K1": tuple(300.0, 2400.0),
> 	"1K0": tuple(300.0, 1300.0),
> 	"500": tuple(500.0, 1000.0),
> 	"250": tuple(600.0, 850.0),
> 	"100": tuple(700.0, 800.0)
>      ];
> }
>
> or automatically at thread startup:
>
> static this()
> {
>      init();
> }
>
> Hope that helps.

See my other reply for a better solution.